Manual Knex 78610 - Education Intro to Levers and Pulleys Teachers Guide (page 53 of 62) (English)

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Education

TEACHER’S

GUIDE

LEVERS AND

PULLEYS

UNDERSTANDING MECHANISMS

78 610

Understanding�Mechanisms:

Levers�and�Pulleys�Teacher’s�Guide

96562-V3-10/14

licensors.

Text: Dr. Alex Wright,

AW Education, Wrexham, LL12 7LR, U.K.

K’NEX Limited Partnership Group

P.O. Box 700

Hatfield, PA 19440-0700

Visit our website at www.knexeducation.co.uk

or www.knexeducation.com

Email: abcknex@knex.com

K’NEX Education is a Registered Trademark

of K’NEX Limited Partnership Group.

Conforms to the Requirements of ASTM

Standard Consumer Safety Specification

on Toy Safety, F963-03.

Manufactured under U.S. Patents 5,061,219;

5,199,919; 5,350,331; 5,137,486.

Other U.S. and foreign patents pending.

Protected by International Copyright.

Understanding Mechanisms

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levers and pulleys

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WARNING:

CHOKING HAZARD - Small parts.

Not for children under 3 years.

A Note About Safety

Safety is of primary concern in

science and technology classrooms.

It is recommended that you develop

a set of rules that governs the

safe, proper use of K’NEX in your

classroom. Safety, as it relates to

the use of the elastic bands should

be specifically addressed.

PARTICULAR CAUTIONS:

Children should not overstretch or

overwind their elastic bands. Over-

stretching and overwinding can

cause the elastic band to snap

and cause personal injury. Any

wear and tear or deterioration of

elastic bands should be reported

immediately to the teacher.

Teachers and children should

inspect elastic bands for deteriora-

tion before each experiment.

Caution children to keep hands

and hair away from all moving

parts. Never put fingers in moving

gears or other moving parts.

Introduction

Your K’NEX Levers and Pulleys kit is

part of a series called “Understanding

Mechanisms”. The series has been

produced to enable Key Stage 2 pupils

to investigate and evaluate some familiar

products, to think about how they work

and to explore the mechanisms that

make them work.

Understanding Mechanisms:

Levers and Pulleys Kit

 • Developedtointroducepupilstothe

way levers and pulleys have been used

in the design of familiar products, this

construction kit also serves to make the

connection between the models the pupils

have built and the science that makes

them work.

 • Workinginpairsorsmallcollaborative 

groups, the kit provides opportunities

for pupils to explore lifting mechanisms

through the use of investigative,

disassembling and evaluative activities

(IDEAs) and focused practical tasks (FPTs).

Teacher Support Materials

 • Developedinitiallyforthenon-specialist 

teacher, the materials included in the

Teacher’s Guide can also be used as a

resource by more experienced teachers

as they develop their own lesson plans.

 • Implementingtheideasandinformation 

included in the Teacher’s Guide can build

your pupils’ knowledge and understanding

of mechanisms, and the ways in which

they can be used to make things move.

 • Keybackgroundinformationisprovided

in “A Quick Guide”, while the Lesson

Notes for each K’NEX model provide more

detailed information and ideas for possible

teaching activities. These teaching activities

have been developed primarily to support

the DfEE/QCA Scheme of Work for Key

Stages 1 and 2 in Design and Technology

and Science, the DATA Design and

Technology Primary Lesson Plans and

Primary Helpsheets.

 • Aglossaryoftechnicaltermsand

scientific definitions is offered as a

resource for the teacher.

 • Eachofthelessonscanbecompleted

in one hour but may be extended using

the suggested Extension and Research

Activities. Useful Internet web sites are

listed to help guide the research activities.

(Note: these were functioning sites at the

time of going to print.)

 • Theteachingactivitiesarealsointended

to encourage the development of key

skills by providing opportunities for whole

class and group discussions, observing,

evaluating and recording through the use

of text and drawings, working with others

to solve problems and using ICT within a

design and technology context.

TABLE OF CONTENTS

Levers 4-38

A Quick Guide to Levers 4-10

Lesson 1: Getting Started 11-12

Lesson 2.1 and 2.2: The Seesaw 13-19

Lesson 3: The Balance 20-25

Lesson 4: The Wheelbarrow 26-29

Lesson 5: The Ice Hockey Stick 30-34

Lesson 6: The Scissors 35-38

Pulleys 39-61

A Quick Guide to Pulleys 39-42

Lesson 7: The Flagpole 43-47

Lesson 8: The Sailboat 48-51

Lesson 9: The Block and Tackle 52-56

Key Terms and Scientific Definitions 57-61

Understanding Mechanisms

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A�Quick�Guide�to�Levers

5C: ‘Moving Toys’ and 6C: ‘Fairground’: and

in Science Units 1E: ‘Pushes and Pulls’; 2E:

‘Force and Movement’; 6E: ‘Balanced and

Unbalanced Forces’.

In addition, working with levers helps children

relate science to the ways familiar machines

work.

What is a lever?

A lever is a rigid beam, bar or rod that is able

to turn or rotate about a fixed point called the

fulcrum. For example:

In the curriculum, the concept of levers may

be used in designing and making activities

associated with the QCA/DfEE Exemplar

Scheme of Work for Design and Technology

Units 1A: ‘Playgrounds’; 1D: ‘Moving Pictures’;

3C: ‘Moving Monsters’; 4B: ‘Storybooks’;

The key parts of a lever are:

 • Fulcrum - a fixed point that allows the

beam to rotate around it and can occur

at any point along the lever. It can be in

the centre, as in a seesaw and a simple

balance; off centre, as in a beam balance

and claw hammer; or at one end, as in

the hinge on a door, nutcrackers and

tweezers.

It is thought that levers have been in use since

prehistoric times. They were most likely used

to help people lift and move heavy rocks in the

Palaeolithic era, to build megalithic structures

such as Stonehenge in the Neolithic period,

and were the basis of the balances used by

early traders and merchants to weigh gold

and other valuable trade goods. Today they

are found in many commonly used devices

such as scissors, pliers, stapling machines,

tweezers, and nutcrackers. Even cricket bats,

hockey sticks, tennis racquets and JCB™

excavating machines use the principle of

levers to make them work.

Fig. 1

Education

A Quick Guide to Levers

• Effort - the force you apply to the lever

to move an object or to overcome a

resistance. The effort can be a push, pull,

squeeze or lift.

 • Load - the mass of the object you need

to move or the resistance to movement

that must be overcome by the lever. This

object provides the force that acts against

the effort. For example, the weight of a

heavy object to be moved, or a piece of

paper that is resisting the cutting action

of the scissor blades, or friction preventing

a nail from being pulled out of a piece of

wood. In fact, the load can be anything

that provides a resistance to your effort.

What can levers do for us?

Levers can…

 • Makejobseasierforustodo.

Lifting or moving a heavy object requires

a large amount of effort. A lever can make

it easier to move the object by reducing

the amount of effort force needed to do

the job. It does this by amplifying the

forces where they are needed. Consider

how you would pull a nail out of a piece

of wood without using a claw hammer,

open a soft drink bottle without a bottle

opener, or move a load of sand without

a wheelbarrow. A clawhammer, bottle

opener and wheelbarrow are each

examples of a lever in action. In each

case they help by reducing the effort

that is needed to perform a specific task.

The longer the lever, the greater the

amplification of the effort forces used

and the easier it is to carry out the job.

Archimedes is supposed to have said,

“Give me a lever long enough and I can

move the Earth”.

 • Changethedirectionof

the applied force.

A push down on one side of a seesaw,

for example, results in the opposite side

moving upwards.

 • Amplifyordecreasetheamountof

output movement.

For example, a small movement at the

effort end of a car park barrier produces

a large movement at the load end.

A push

up here…

…makes

this side

move down

Education

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A�Quick�Guide�to�Levers

 • Increasethespeedtheloadmoves.

This characteristic of a lever can be seen

in the seige engines known as trebuchets

that were used to throw large stones at

castle walls in medieval times.

Figure 2 shows a large medieval trebuchet -

a giant lever in which the fulcrum is off-centre.

A massive effort is applied to move a small

load. The end of the long arm on the load

side is made to move very quickly, accelerating

the sling holding the load and propelling it

forward over a long distance. Trebuchets

caused enormous damage because they

were able to toss objects at castle walls

at speeds in excess of 160 kilometres an

hour. Fishing rods and hockey sticks use

the same principle.

Visit http://www.flyingpig.co.uk/Pages/

lever2.htm to see a trebuchet in action.

Visit http://wwwpbs.org/wbgh/nova/

lostempires/trebuchet/builds.html to see

photos of the reconstruction of a trebuchet.

Are all levers the same?

There are three basic types of lever: 1st Class,

2nd Class and 3rd Class levers. They all share

the common components of a rigid rod or

beam, fulcrum, effort and load. They differ only

in the relative positions of the fulcrum, effort

and load.

1st Class Levers

Key facts

 • In a 1st Class lever the fulcrum is

positioned between the effort and the load.

 • Theeffortandloadmoveinopposite

directions. 1st Class levers, therefore, can

be used to change the direction of an

applied force. For example a downward

push on one end of the lever can result in

an upward push or pull at the other end.

 • Theeffortforcecanbeamplifiedby

increasing the length of the effort arm.

The longer the effort arm, the easier it is

to move the load.

 • Thelongertheloadorresistancearm,the 

faster the load can be made to move. For

example: the trebuchet.

Fig. 2

Fig. 3

Education

A Quick Guide to Levers

The Principle of Levers identifies a relationship between the effort, the load and the distance of

each from the fulcrum. This principle states that a lever is balanced (or in a state of equilibrium) when:

Key facts

In a 2nd Class lever:

 • The load is between the effort and

the fulcrum.

 • The effort and load move in the

same direction.

the effort x its distance from the fulcrum

on one side

the load x its distance from the fulcrum

on the opposite side

A pair of scissors is an example of two 1st

Class levers working together. Squeezing the

handles together produces the effort, the hinge

is the fulcrum and the resistance of the card

being cut is the load. The strongest cutting

action is nearest the hinge.

Wire cutters have longer arms than scissors.

This design modification generates a much

more powerful cutting action by increasing the

length of the effort arm.

Fig. 4

2nd Class Levers

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A�Quick�Guide�to�Levers

3rd Class Levers

Compound 2nd Class levers.

Fig. 5

Nutcrackers are made from two 2nd Class

levers. The effort is applied to the effort arms

when a hand squeezes them together, the load

is the resistance of the nut’s shell to cracking

and the fulcrum is the hinge.

Key facts

In a 3rd Class lever:

 • The effort is between the fulcrum and

the load.

 • Theeffortandloadmoveinthe

same direction.

 • 3rdClassleversalwaysincreasethe

speed the load moves because the effort

is always positioned closer to the fulcrum

than the load. (See Fig. 5). Applying the

effort close to the fulcrum requires a large

input force but the effort arm only moves

through a small distance. The opposite

end of the lever (or load arm), however,

moves through a greater distance, at a

faster speed, but with less force.

In Fig. 6 the load is located twice as far

from the fulcrum as the effort. In this

example the load moves twice as fast as

the effort, because it must move double

the distance in the same amount of time.

That’s the trade off. In order to get greater

speed, a large effort force is needed to

move a small load.

Fig. 6

• 2nd Class levers always amplify the output

force. In this type of lever arrangement,

the load is always closer to the fulcrum

than the effort force. This means the effort

arm will be longer than the load arm (see

diagram). The longer the effort arm, the

more the effort force is amplified where

it is needed, so making it easier to move

the load. With a 2nd Class lever, therefore,

it is possible to move a large load with a

smaller effort.

Education

 • 3rdClassleversarenotasefficientas

other levers because the load is always

further from the fulcrum than the effort.

A Quick Guide to Levers

Compound 3rd Class levers

A small movement of the fingers squeezing the

two arms together produces a long movement

at the tips of the tweezers in order to grip an

object such as a hair. The load is the resistance

of the hair.

For example, raising a fish with a fishing

rod actually requires more effort force

than just lifting the fish using only a hand-

held line. A fishing rod, however, helps by

lifting the fish quickly. A small movement

of your hands near the fulcrum produces

a large movement at the tip of the rod, but

both move in the same period of time. As

a result, the tip of the rod (and the fish

attached to it) actually moves more quickly

than the hands and this quick action can

help land the fish before it escapes.

Some machines use more than one type of

lever in their working mechanisms.

Nail clippers involve a double action - the

handle presses down onto the tweezer-like

action of the cutters. The handle is a 2nd Class

lever while the cutter is a 3rd Class lever.

The head of the claw hammer is a 3rd Class

lever while the claw is a 1st class lever.

Education

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A�Quick�Guide�to�Levers

Useful Web Sites.

http://www.enchantedlearning.com/physics/

machines/Levers.shtml This web site has

some very simple animated drawings of the

different types of levers in action.

http://www.coe.uh.edu/archive

The University of Houston archive of lessons.

Go to: Collection > Science > Lesson plans >

Simple Machines.

www.flying-pig.co.uk A general site for simple

machines offering useful animated drawings of

mechanisms in action.

www.howstuffworks.com A library of

information on different types of machines.

Useful background information for teachers –

you will need to use the search facility to find

information.

www.mos.org/sln/Leonardo/

InventorsToolbox.html A useful site covering

general information on levers and other

simple machines.

www.smartown.com/sp2000/machines2000/

Simple machines made simpler. A good

introduction to simple machines made by

school children.

The main boom is a

3rd class lever.

The excavating arm is

a 1st class lever.

Fulcrum

Load

Effort

The excavating arm is

hinged onto the main boom

and is pulled and pushed

by the hydraulic cylinder

attached to the main boom.

The arm and bucket

operating mechanism are

examples of 1st class

levers in action.

Fulcrum

Load

Effort

The main boom and

excavator arm together

make up a 3rd class lever.

The effort force is the push

and pull provided by the

hydraulic cylinder between

the digger chassis and the

moving arm.

JCB excavators that use a series of hydraulically operated arms are good examples of multiple

levers in action.

Education

Lesson�1:�Getting�Started

Lesson 1: Getting Started

Time: 1 hour

LearningObjectives - Children should learn:

 •toassemble,joinandcombinematerialsandcomponents

 •thatconstructionmaterialcanbeusedtotryoutideas

 •torecogniseshapesandtheirapplicationinstructures

 •todrawandlabeldesigns

Vocabulary

dimensional, 2D, 3D, cubes,

cuboids, cylinders, symmetrical, Rods,

Flexi-rods, Connectors, Spacers, Hubs,

Tyres, components, right angles, stable,

rigid, flexible, functions

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding Mechanisms:

Levers and Pulleys kit with Building

Instructions booklet

Possible Teaching and Learning Activities

Introduction

This lesson provides children with the opportunity to

investigate how K’NEX construction materials may be

used to create different 2D and 3D shapes. It could also

contribute to cross-curricular activities, including:

(i) Mathematics: shape and space, movement

and angles.

(ii) Literacy: speaking and listening, describing

observations.

Teacher’s Notes

For many children, this may be their

first opportunity to explore, experience

and experiment with the K’NEX

materials they will be using in their

classroom activities. This includes

learning the names of the different

components and their functions.

Note: K’NEX Rods, Flexi-rods,

Connectors, Spacers, Hubs and

Tyres are always capitalized.

The Building Instructions booklet

provided in each set includes a

building tips page, which offers

guidelines for connecting the individual

pieces. You may want to provide

time for the children to practice

connecting the different components.

It is crucial that they grasp the building

concept at this stage so that

frustrations are avoided later.

Working in Groups of 2-3

 •AskthechildrentousetheK’NEXmaterialsintheirkit

to make and name different:

 •2Dshapes

 •3Dshapes–e.g.cubes,cuboidsandcylinders

 •Symmetricalshapes/mirrorimages

 •Askthechildrenwhatsortsofshapesmightbeused

to make stable structures.

 •AskthechildrentolookattheirK’NEXcomponentsand:

 •Identifythosethatcontainanangleof:

(i) 90 degrees

(ii) less than 90 degrees

(iii) more than 90 degrees

 •Whatsortofshapescantheymakewith

these components?

 •IdentifyConnectorsthatallowthemtobuild

shapes containing right angles.

 •IdentifyConnectorsthatcanbeusedtomake

rigid and flexible joints.

 •Identifycomponentsthatcanbeusedtomake

things move.

NOTE: This lesson, which introduces children to the K’NEX

materials and building techniques, is included in each of the

Understanding Mechanisms Teacher’s Guides. If your class is

already familiar with the K’NEX Understanding Mechanisms

kits you may omit it and begin with Lesson 2.

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Education

Provide some basic guidelines for

maintaining all the pieces in the set

for future use. At least 5 minutes will

be needed at the end of each lesson

for cleaning up the materials.

 •Askthechildrento:

 •Makeatall,stablestructure.

 •Makeamodelwithmovingparts.

 •Askthechildrentomakedrawingsoftheirmodelsand

to label them showing:

 •Howandwheretheymadethestructurestable.

 •Howtheirmodelworksandthemovementsthe

model makes.

 •Childrenmaybeencouragedtothinkaboutanddiscuss

what they are doing through facilitating questions

such as:

 •Whatdoesthemachinedo?

 •Whatarethefunctionsofthemovingparts?

 •Howarethemovingpartsconnectedorhowdo

they make other parts move?

 •Whatarethemovingpartscalled?

 •Whattypesofmovementsdothemoving

parts make?

Plenary session

 •Choosearangeofmodelsthatmaybesharedwith

the class.

 •Possiblequestionstoask:

 •Howdidyoumakethis?

 •Wereanypartsofthemodeldifficulttomake?

 •Whatpartsofyourmodelareyoupleasedwith

and why?

 •Whatshapesdidyouuseinyourmodel?Why?

 •Howstableisyourmodel?Howdidyoutest

your model?

 •Whatmovementswereyoutryingtomakeand

how did you make them work?

 •Whatcomponentsdidyouusetomake

the movements?

 •Whatothertypesofmachineshaveyouseenin

which these components were used and what

did the machines do?

 •Whatwouldyoudodifferentlynexttime?

Teacher’s Notes

Using labelled drawings is an

important communication skill that

needs to be learnt. Emphasize to the

children that it is not important for

their drawing to look exactly like the

K’NEX or any other machine they are

investigating. It is more important

for their drawing to show how the

machine works. For example, they

should show how the moving parts

connect to each other.

Interpreting 2D drawings to construct

3D models is an important skill to be

learnt and from the outset children

should be asked to say what

movements/functions their model

will perform before they build and

investigate the actual mechanisms.

Education

Lesson�2.1�and�2.2:�The�Seesaw

1st Class Lever

Time for each lesson: 1.5

hours

Note: Lesson 2.1 is appropriate for Key Stage 1 and as an

introductory activity for Key Stage 2 children. Lesson 2.2 is

more appropriate for Key Stage 2.

LearningObjectives - Children should learn:

 •pushesandpullsareexamplesofforces

 •toobserveanddescribemovementsinasimplemachine

 •torelatesciencetothewaysfamiliarmachineswork

 •tocarryoutasimpleinvestigation

Vocabulary

1st Class lever, load, effort,

fulcrum, pivot, centre, off centre,

beam, rigid, up, down, raise, lower,

lift, opposite, direction, turns, rotates,

push, pull, force, weight, force meter,

simple machine

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Levers and Pulleys kit

and Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• 2 paper cups or 2 pieces of foil

• Coins, paperclips or weights to use

in the cups

• 5 Newton force meter or weights

• A collection of devices that use the

lever principle

Useful Internet Web Sites:

Please refer to Page 10 of A Quick

Guide to Levers.

Lesson 2.1 for Key Stage 1

Possible Teaching and Learning Activities

Introduction

The activities outlined in this lesson may be used to support

the QCA/ DfEE Exemplar Scheme of Work for:

Design and Technology Unit

•1A:Playgrounds

   •1D:MovingPictures

   •3C:MovingMonsters

   •4B:Storybooks

   •5C:MovingToys

   •6C:Fairground

Science Units

•1E:PushesandPulls

•2C:ForcesandMovement

   •6E:BalancedandUnbalancedForces

Teacher’s Notes

Key Stage 1 and 2 Activities

The suggested activities are suitable

for Key Stage 1 children and provide

opportunities for children to investigate

and use words and phrases related to

forces and movement. For example:

push, pull, turn, direction, distance,

force, up, down, opposite. Activities

for older Key Stage 1 and Key Stage 2

children are provided on Page 17.

Lesson 2: The Seesaw

Education

levers and pulleys

website: www.knexeducation.co.uk

Whole Class

 •Askthechildrentotalkaboutthetypesofmoving

equipment they can find in playgrounds.

  •Encouragethechildrentodescribethetypesof

movement each piece makes. Answers may include:

up/down; back and forward; swing; rocking; round and

round/rotates/circle.

  •Askthechildrenwhattheyhavetodotomakethe

equipment carry out the movement. Answers may

include: push or pull to start or stop the movement.

Working in Groups of 2-3

 •AskthechildrentobuildtheK’NEXSeesaw.Youmay

wish to limit the K’NEX building activity to about 10-15

minutes. This will encourage the children to work

cooperatively in order to complete the task within

the allotted time frame. Allow them a few minutes to

investigate how their model works.

 •Ask,“Cantheseesawmovewithoutbeingpushed

or pulled?”

 •Askthechildrentomakelabelswiththewords‘push’,

‘pull’, ‘push and pull’ written on them. Each group

should discuss where, on their K’NEX seesaw model,

they should stick the labels in order to show how they

make it move.

 •Askeachgrouptodescribe:

* What they did to make the seesaw move.

* The movements produced by the seesaw.

* The shapes used to make the seesaw strong

and rigid.

* Why they think their model has a wide base.

This introductory discussion provides

an opportunity to assess children’s

knowledge and understanding of:

(a) simple mechanisms and their

use of technical vocabulary in

describing movements,

(b) forces, pushes and pulls.

* Possible answer: We pushed

one end.

* Possible answer: When we

pushed one end down, the

other end went up; when we

pushed and pulled one end

the opposite end went up

and down.

* Triangles.

* Possible answer: It helps to

make the structure stable/

stops it falling over.

Whole Class

 •Explaintothechildrenthataseesawisanexampleof

a lever and that if we know what to look for we will

find levers being used everywhere. Use the seesaw

Lesson�2.1�and�2.2:�The�Seesaw�

Education

model to identify the key parts of a lever - simply a rigid

beam or rod that turns /rotates/ pivots about a point.

 •Helpthechildrentounderstandthatweevenhave

levers in our own bodies – our arms and legs are levers.

 •Talkabouthowleversareprobablyoneoftheoldest

machines known – perhaps used by people in

prehistoric times to move large rocks or to help get

mammoths out of pit traps.

So what do levers do?

One thing they do is to make it easier to lift things.

Discuss how hard the children might find it to lift their work

partner but yet how easy it is to lift them up when they use

a seesaw.

Youmaywanttoaskonechildtotakethelidoffatinof

powder paint or cocoa powder using only their fingers. Then

provide a screwdriver/spoon to act as a lever to remove the

lid. Ask the rest of the class to carefully observe what hap-

pened when the lever was used to remove the lid.

See A Quick Guide to Levers for additional information.

 • Explaintotheclasstheywillnowexplorehow

levers work.

 • UseaK’NEXSeesawmodeltoidentifyand

demonstrate the three main components of a lever:

effort, load and fulcrum.

 • Youmaywanttodrawadiagramontheboardto

reinforce the concepts.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 2: The Seesaw

Education

Teacher’s Notes

The children should be aware of the

weight, or force, made by the weighted

paper cup on their hand. The activity

also provides an opportunity to

introduce children to the idea that

weight is also a force. The effect of

using a weight is the same as pushing

down with a finger.

It may be useful to create a word

board with cards that have the word

on one side and a short explanation

on the reverse side for children to use

when needed.

Working in Groups of 2-3

 •Askeachgrouptopreparestickersandlabeltheir

seesaw model.

F - Fulcrum

L – Load

E – Effort

Each group will need 2 paper cups (or pieces of foil) and

some weights (paper clips/coins/standard weights).

1. Feel the load:

 •Askonechildfromeachgrouptoplacethebackoftheir

hand and arm on the desktop. Another member of the

group then places the paper cup/foil containing the

weights on the fingers of their partner’s hand who then

lifts the cup up from the surface of the desk. Each child

tries the exercise in turn.

   •Whatdidtheyfeel?

   •Didthecupfeelheavy?

2. Use the lever:

 • Askeachgrouptoplacetheweightedpapercupatone

end the seesaw. What happens to the end of the seesaw

with the load attached to it? Each child in turn pushes

down at the opposite end and notices what happens to

the load. Possible questions to ask:

  •Diditfeeleasierormoredifficulttolifttheweighted

paper cup this time?

  •Whatwasthedirectionmovedbytheirpush(effort)?

  •Whatwasthedirectionmovedbythepapercup(load)?

 • Askthechildrentotaketheirlabelsandplacethemin

the appropriate locations on the model to identify the

fulcrum, load and effort. Ask the groups to make and

add two arrow labels to their models to show the

direction of movement of the effort and load forces.

An alternative method is to wrap the

weights/coins in foil and attach the foil

parcels to the seat of the seesaw with

an elastic band. If you use elastic

bands in the classroom please review

the safety guidelines, outlined at the

beginning of this guide, regarding

their safe use by the children.

Talk about how one end of the seesaw

goes down when the weighted paper

cup is placed at the load end but will

not move until there is a push (an

applied effort) at the opposite end.

To lift the load up they must push

down. In other words, the lever has

helped change the direction of the

movement and the applied force. The

use of the directional arrows may help

the children visualise what is happening

as they record their observations and

make labelled drawings of their model.

Lesson�2.1�and�2.2:�The�Seesaw

Education

levers and pulleys

website: www.knexeducation.co.uk

Lesson 2: The Seesaw

 • Talkabouthowleverscanbefoundeverywhere,butthey

do not all look like seesaws. Other examples of levers

include scissors to cut paper, a claw hammer to pull a

nail out of piece of wood, a stapler, an oar used to row

a boat and even their own arms and legs.

Extension Activity 1

Some children may feel it was easier to move the paper

cup using the lever than without it. Discuss how they might

be able to carry out a fair test to verify their ideas.

Teacher’s Notes

If time allows ask children to

investigate levers on selected

Internet web sites. For example

www.enchantedlearning.com/physics/

machines/levers.shtml

The children could be asked to

come up with different ideas to

measure the load and effort. These

ideas might include using non-statutory

measurements such as the number of

paperclips/coins in each paper cup,

or using force meters.

 • Askthechildrentodescribeandexplaintheir

observations in written text and/or verbally. They should

include labelled drawings of their model with arrows to

indicate movements and use the correct terminology to

describe the different components.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work could

be recorded using a digital camera.

Extension Activity 2

Discuss what rules the children would have to make if three

of them were to use a seesaw at the same time. Where

would they have to sit? How might they use their K’NEX

seesaw model to test their ideas?

Lesson 2.2 for Key stage 2

Possible Teaching and Learning Activities

The following activities are more suitable for older Key

Stage 1 or early Key Stage 2 children. The starting point is

the K’NEX Seesaw model used in the previous lesson.

Working in Groups of 2-3

Making lifting and moving easier:

 • Askeachgrouptomodifytheirseesawmodelsothat

the load is positioned closer to the fulcrum.

 • Explaintothechildrenthefulcrumisnow‘off-centre’,

making the arms unequal in length. In the original

model the fulcrum is positioned in the centre of the

beam, making the arms equal in length.

 • Askthechildrentopredict,givingtheirreasons,if

this change will make any difference in the effort they

need to use to lift the load. How will they test their

predictions? Write their predictions on the board for

later discussion.

The children could be asked to work

the modification out for themselves

or they could be told to replace

the yellow Rods on the load side

with shorter blue or white ones.

You may wish to review what the

children did in 1: ‘Feel the load’

and 2: ‘Use the lever’ described in

Lesson 2.1.

Education

 • Tryitandsee.Weretheirpredictionscorrect?

Teacher’s Notes

The children should find that it

requires a much smaller effort (a

push or weighted paper cup) to lift

the load. If they use the weighted

paper “effort” cup from the earlier

activity they will find it is too heavy.

At this point you may wish to introduce

the idea of input, process and output

as applied to machines. In the case of

a lever:

• the input is the amount and

direction of the effort force

• the process is the lever

mechanism and

• the output is the direction and

amount of force produced at the

‘load’ end of the lever beam.

 • Askthechildrentousewrittentexttodescribe

and explain their observations. They should include

labelled drawings of their model with arrows to indicate

movements and they should use the correct terminology

to describe the different components.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work could

be recorded using a digital camera.

Whole Class

 •Discusshowitnowrequiresmuchlessefforttoliftthe

load when the effort is applied a greater distance from

the fulcrum than the load.

 •Thisformofleverdesigndiffersfromthatoftheseesaw

in which the load and effort are applied equidistant from

the fulcrum.

 •Talkabouthowmuchthe‘effort’endnowmoves

compared to the ‘load’. This demonstrates another

function of levers - to increase (amplify) or decrease

movements depending on which end of the lever is

used to apply the effort.

Lesson�2.1�and�2.2:�The�Seesaw

Education

Lesson 2: The Seesaw

•Askthechildreniftheythinkitwillbehardertoliftthe

load when it is placed a long distance from the fulcrum.

Explain that they can reverse the load and effort ends

of their seesaw lever model. Reposition the labelling

stickers to the new arrangement and repeat the

activities as before.

 •Askthechildrentodescribeandexplaintheir

observations. They should include labelled drawings

of their model with arrows to indicate movements and

use the correct terminology to describe the different

components.

Extension Activity 1

Ask the children to use a force meter to measure the effort

force needed to lift the load in the three different situations

outlined above. If two force meters are available per group,

one force meter could be used to apply the load and the

other force meter could be used to measure the effort.

Record the results on the board and discuss the results.

Plenary

Have a quiz on levers in which the children must use

the correct technical vocabulary.

Ask the children to identify ‘levers in action’ from a

collection of common devices used in school and at

home. The names of the devices are written on cards,

which are placed face down on a desk. A child selects a

card naming the lever device to which they must respond.

They must describe what the device is used for, how it

works and be able to identify the load, fulcrum and where

the effort is applied.

Teacher’s Notes

Children are often surprised how much

effort is needed to lift a load positioned

a long way from the fulcrum, especially

when effort must be applied close to

the fulcrum. The other surprise comes

when the load end pivots round very

quickly, often hitting the back of their

hand. To explore this further, some

groups could be asked to use blue

Rods and others white Rods instead

of the yellow ones in the original

building plans.

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�3:�The�Balance�

1st Class Lever

Time for each lesson: 1 - 1.5

hours

LearningObjectives - Children should learn:

 •toobserveanddescribemovements,directionandtypes

of forces working in a lever mechanism

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

balance, unbalanced, lever, pivot,

fulcrum, beam, load, effort, direction,

movement, up, down, weight, mass,

level, force, Newton, friction, opposes,

motion, gravity, horizontal, stationary

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Levers and Pulleys kit

and Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Washers, paperclips (all of an equal

size) or slotted gram masses to

hang from the balance arms

• Ruler

Useful Internet Web Sites:

Please refer to Page 10 of A Quick

Guide to Levers.

Possible Teaching and Learning Activities

Introduction

The activities outlined in this lesson may be used to support

the QCA/ DfEE Exemplar Scheme of Work for:

Design and Technology Unit

•1A:Playgrounds

   •1D:MovingPictures

   •3C:MovingMonsters

   •4B:Storybooks

   •5C:MovingToys

   •6C:Fairground

Science Units

•1E:PushesandPulls

•2C:ForcesandMovement

   •6E:BalancedandUnbalancedForces

Whole Class

 •Talkabouthowbalancesandotherweighingdevices

with which the children may be familiar from other

lessons, (for example: mathematics), have been used

for centuries. Help the children to understand that

distributing weight equally, using a form of balance,

can also make it easier to carry heavy loads. Ask the

children to look at the man in the photograph on Page

4 of the K’NEX Building Instructions booklet.

Teacher’s Notes

The large load is split into two equal

portions and evenly balanced across

his shoulders.

Education

 •Askthemwhyitmightbeeasierforhimtocarryloads

in this way. What would happen if the man’s load were

not balanced on each side of the pole?

Working in Groups of 2-3

 •Explainhowtheclasswilldiscoverhowabalance

works by building and investigating a K’NEX

model balance.

 •AskeachgrouptobuildtheK’NEXBalancemodel

shown on Pages 4-5 of the Building Instructions

booklet. Allow them time to investigate how their

model works.

Whole Class

 •TalkaboutthesimilaritiesbetweentheK’NEXBalance

model and the Seesaw model, investigated in a

previous lesson.

 •Discusshowthebalanceisanexampleofalever.

 •Askthechildrentopreparestickylabelsandusethem

to identify the different parts of their balance model.

F = Fulcrum L = Load E = Effort Beam

 •(Optional)Explainhowthebalanceandseesaware

examples of a 1st Class lever and that there are 3

different types of levers: 1st Class, 2nd Class and 3rd

Class levers. Tell the children that they will be able to

investigate the different lever types in other lessons.

Working in Groups 2-3

 • Askthechildrentoremovethegreyhangingtrays(grey

pulley wheels) from their model and push the red and

orange hangers to the end of the balance arms.

 • Oncethetwoarmsarestationary,askthechildrento

observe and describe what the model is doing, using

the correct vocabulary.

 • Whathappenswhenoneendofthebalancearmis

given a small push/has a force applied?

 • Thechildrenshouldbeaskedtoexplaintheir

observations.

 • Discusshowthisactivitydemonstratesthatanobject

will remain stationary until a force acts on it.

Teacher’s Notes

The balance model does not move

because the forces acting on both arms

are balanced. When a force

is applied to one side it will move

because the forces are now

unbalanced. The arm to which the

force has been applied moves in the

direction of the applied force. If a

weight is used, instead of a push, it

will also causes the arm to move.

Weight is also a force.

The balance will remain stationary, or

at rest, until a weight is loaded on one

side or a force is applied to one side.

If that weight or force is larger than the

weight or force on the opposite side

then the forces acting on the balance

arm will become unbalanced and the

Teacher’s Notes

If the load is not balanced evenly, one

side will hang down lower than the

other and make it difficult to carry.

Lesson 3: The Balance

levers and pulleys

website: www.knexeducation.co.uk

Education

Teacher’s Notes

If time allows you may wish to

demonstrate other examples of objects

that remain stationary and have clearly

identifiable and familiar forces acting on

them. For example, an object

suspended from a string, thread or

elastic band will remain in that position.

If, however, the weight of the object

is increased, a point will be reached

at which the string will break and the

object will fall. At the point at which

the string breaks, the forces acting on

it are unbalanced. In other words,

the weight of the object (load) is now

greater than the resistance (load

bearing capacity) of the string.

Talk about how mechanisms such

as levers (balances) and familiar

playground equipment or machines

also need to have forces applied to

them to make them move. All machines

need a force to be applied to them to

make them work.

 • Askthechildrentoidentifywhatotherforcesmayhave

acted on the balance to stop it moving.

* What force slows up the arms and eventually stops

them moving?

 * Frictioninthepivotjointand

air resistance.

Friction is the force that opposes

movement. In the pivot joint, friction

has the effect of slowing down the

movement. It acts just like a brake.

If both arms are of equal weight,

then the force due to gravity acting

on both sides will be equal and, in

theory, the arms will come to rest in

a horizontal position.

* Why do the arms eventually stop in a

horizontal position?

* Both arms are equal in weight

and so the forces acting on

each side are equal.

* What force is acting on each arm now?

* Gravity.

balance arm will move in the direction

of the larger force. This is a general law

of physics.

Lesson�3:�The�Balance

Education

Exploring the K’NEX balance model

 • Replacethehangingtrayssothattherearetwopulleys

on one side and one on the other side. Push both

hanging trays to the end of their arms and observe,

record and explain what happens.

 • Posethequestion,“Whatdoyouhavetodotobalance

the forces in the model?”

Teacher’s Notes

The children should note that the

heavier tray goes down while the

lighter tray moves up. They should

also report that this is the result of

unbalanced forces in action.

The children may either add, or

remove, a grey pulley to one or the

other side in order to make the weights

on both sides equal. The children

should be encouraged to discuss their

observations in terms of balanced and

unbalanced forces.

 • Askthechildrentoreturntotheir‘unbalanced’model

with two grey pulleys on one side and one on the other

to find a different way to balance their model without

adding or removing grey pulleys. They can slide the

hanging trays along the arms.

The children should be able to find

that by sliding the heavier hanging

tray closer to the fulcrum, the balance

model will again become balanced.

Discuss the children’s findings

with those obtained in a previous

investigation of the K’NEX Seesaw

(Lesson 2.2: Making lifting and moving

easier) in which they discovered that

a small effort applied a long distance

from the fulcrum can be used to lift

a heavier load positioned close to

the fulcrum.

Whole Class

 • Askthechildreniftheirresultsmightsuggestageneral

rule for making a balance work.

 • Discusswiththeclass

  •Howwilltheytesttheirrule?

  •Whatwilltheymeasure?

  •Howmanyreadingsdotheyneedtotake?

  •Howwilltheyrecordtheirresults?

If time permits, each group could

work individually. Alternatively, the

class could share results leading to

a general class discussion on their

interpretation.

You may also decide to suggest that

the children use a table template, such

as the one shown on Page 24, in which

to record their results.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 3: The Balance

Education

Lesson�3:�The�Balance

Younger children might use squared graph paper to record and visualise their results.

For example:

The children measure the relative distance they placed the grey K’NEX pulley hangers, the

number of washers or paperclips or the value of the masses used to balance their model, in

the appropriate distance measurement, as measured from the fulcrum. The blue connecting Rod

on the hangers could be placed through the washers or paper clips to prevent them falling off.

For those children who are unable to come up with their own ideas, you might suggest they

keep one K’NEX pulley at one end and find the positions on the other arm to balance 2, 3 and

4 K’NEX pulleys.

Using squared graph paper:

Using a template:

Education

 • Discusstheresultsoftheirinvestigationinwhichthey

explored balancing the forces acting on the model. They

should have found that when balanced, the forces on

one side must equal the forces on the opposite side.

 • Askthechildrentomakelabelleddrawingsoftheir

balance model showing the positions of the fulcrum,

effort and load and the directions in which the forces

are acting. They should describe and explain their

observations using appropriate scientific and

technological vocabulary.

Problem solving activity

Children could be set the task of applying their rule to find

the weight of an unknown object using only one 10g mass.

Plenary

Ask some children to describe and explain how they solved

the weighing problem.

Teacher’s Notes

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 3: The Balance

Education

Lesson�4:�The�Wheelbarrow�

2nd Class Lever

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

lever, pivot, fulcrum, beam,

handles, effort, load, lift, weight,

force, Newton, heavy, object,

force meter, design specification,

compare, modify, 1st Class lever,

2nd Class lever, labelled drawings

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Introduction to Simple

Machines: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Aluminium foil or cling film

• A pile of small washers, paper

clips or plastic beads or other

small objects that are awkward to

carry by hand

• Force meters

Useful Internet Web Sites:

Please refer to Page 10 of A Quick

Guide to Levers.

Possible Teaching and Learning Activities

Intoduction

In this lesson children investigate the science used in the

design of a wheelbarrow and how knowledge and under-

standing of the lever principle can help them modify and

improve its design for a different purpose.

Whole class

 •Explainthatalthoughleverscomeindifferentforms,

they all use the same basic principle: if a heavy object

(load) is positioned close to the fulcrum, less force

(effort) is needed to move it.

For example, a door, a paper guillotine, a stapler and

nutcrackers all make use of the lever principle but they

all have very different functions.

 •Askthechildrenifitiseasiertoopenadoorbypushing

close to the hinge or at the handle? Explain that the

door hinge is the fulcrum, the weight of the door is the

load and the effort is applied where you push. Review

their findings from previous lessons – if the effort is

applied a long way from the fulcrum work will be easier.

Teacher’s Notes

If time is available, or as prior

learning in an ICT lesson, children

could use the Internet to research

different uses of levers.

Education

Whole class

 •Reviewhow,inpreviouslessons,thechildren

investigated the type of lever used in a seesaw and a

balance. Explain that in this lesson they will investigate

a different type of lever and discover how it operates

in a wheelbarrow. Children may be familiar with a

wheelbarrow but they may not recognise it as a lever

in action.

Working in Groups of 2-3

 •AskeachgrouptobuildtheirK’NEXwheelbarrowmodel

and investigate how it works.

 •Thechildrenshouldlinethetrayoftheirwheelbarrow

with aluminium foil or cling film. This will prevent the

washers, or other small objects, from falling out as they

are moved in the wheelbarrow.

 •Questionstoask:

  •Whatarewheelbarrowsusedfor?

  •Whattypesofloadsarenormallycarried

in wheelbarrows?

  •Howarewheelbarrowsloadedandunloaded?

  •Howgoodisthewheelbarrowdesignforits

intended purpose?

  •Howgoodisthewheelbarrowforliftingandmoving

heavy loads? (If they did not have a wheelbarrow

how might they lift and move a heavy load?).

 • Thechildrenshouldbeencouragedtorecord,describe

and explain their observations, using labelled drawings

where possible.

 • Askthechildrentoinvestigatethewheelbarrowasa

lever and to identify and label the positions of the

fulcrum, load and effort on their model using the dot

stickers or masking tape labels.

 • Whatarethedesignfeaturesthatmakeawheelbarrow

a good machine for lifting and moving heavy loads?

 • Reviewwiththechildrenhowtheydiscoveredinthe

seesaw and balance investigations that a large

weight/force close to the fulcrum could be moved by

a smaller weight/force further away from the fulcrum.

 • Howdothepositionsoftheeffort,fulcrumandload

compare to those they found in their K’NEX balance

and seesaw models?

Teacher’s Notes

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

Wheelbarrows are normally used to

carry loose materials such as sand, soil

or rubble. The wheel not only reduces

friction and makes it easier to move

over surfaces, but it also acts as a

pivot to tip up the wheelbarrow to

empty it. The tray has a sloping front

end to make it easier to tip out the

loose materials.

The handles used for lifting the load

are placed much further from the

fulcrum than is the load being carried.

Force meters could be introduced

to enable the children to compare

the force needed to vertically lift the

wheelbarrow with its load, versus the

force needed to lift the load using

the handles.

In wheelbarrows the load is

positioned between the lifting effort

force and the fulcrum. This means that

the lifting force will always be amplified.

The load and the effort also move in

the same direction.

Lesson 4: The Wheelbarrow

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�4:�The�Wheelbarrow�

Teacher’s Notes

The wheelbarrow, although a lever

in action, is a different type of lever

from that found in the balance and

seesaw. In those simple machines

the fulcrum is between the effort and

load. Talk about how both types of

levers share the same features – a

rigid beam that rotates about a

fulcrum, effort and load.

See the ‘A Quick Guide to Levers’ for

additional information.

Whole Class

 • (Optional)Explainhowleverscanbeclassified,usingthe

relative positions of the effort, fulcrum and load, into 1st,

2nd and 3rd Class levers.

The seesaw and balance are examples

of 1st Class levers in which the fulcrum

is between the effort and load. In 2nd

Class levers the load is between the

fulcrum and effort.

See the ‘A Quick Guide to Levers’ for

additional information.

If time is available, or in a prior ICT

lesson, children could use the Internet

to research different uses of 2nd Class

levers. For example: a door, stapler,

bottle opener and nutcrackers.

Working in Groups of 2-3

 • Whatotherexamplesof2ndClassleverscanthe

children find in the classroom, at home or from an

Internet search?

 • Identifythepositionsofthefulcrum,loadandeffort

and explain how each machine works and why it is a

2nd Class lever.

Extension Activity 1

Design problem

 • Anewwheelbarrowisneededtomoveevenheavier

loads. What changes should be made to their present

design to enable it to move heavier loads without

increasing the effort needed to lift the handles.

 • Howwillthechildrentesttheirdesigntoensurethatit

meets the new design brief?

 • Theyshouldbeabletodescribeandexplainwhytheir

design will be able to lift and move heavier loads.

 • Thechildrenshouldbeencouragedtouselabelled

drawings wherever possible.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

2nd Class Lever

Education

Extension Activity 2

The wheelbarrow without a wheel

If time is available, or during an ICT lesson, children could

use the Internet to research the “travois”.

Not all cultures used the wheel to help move heavy loads.

Many nomadic peoples used a different method, similar in

principle to the wheelbarrow, but without the wheel. For

example, Native Americans on the Great Plains used the ‘tra-

vois” to move their household belongings. This device

is a frame made from a pair of long poles hitched to a dog

or horse. The load is strapped across the poles, while the

ends of the poles simply drag along the ground behind the

animal. It is easy to assemble, to take apart when not in

use, to repair and makes use of readily available materials.

Discuss how the travois design compares with that of the

wheelbarrow. The children might consider how they are

used and how they meet the needs of the users and

identify their similarities and differences.

Plenary

Share designs, features and discuss the science behind a

good wheelbarrow design.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 4: The Wheelbarrow

Education

Lesson�5:�The�Ice�Hockey�Stick�

3rd Class Lever

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

 •tocarryoutaproblemsolvingactivity

Vocabulary

3rd Class lever, pivot, fulcrum,

effort, load, resistance, handle,

weight, force, object, stationary,

rest, still, design, specification,

compare, labelled drawings,

balanced, unbalanced, friction,

air resistance, fair test

Possible Teaching and Learning Activities

Introduction

The activities in this lesson may be used to support the

QCA/DfEE Exemplar Scheme of Work for Science:

•Unit4:Friction

 •Unit6E:BalancedandUnbalancedForces

Whole Class

 • Discusshowthereareanumberofsportsthatuse

clubs, bats or sticks to strike balls or other objects,

either over a long distance or at high speed. Examples

include sticks to score goals in ice hockey, or bats to

hit the ball to the boundary in cricket.

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Introduction to Simple

Machines: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Measuring tape

You will need:

• Hockey stick (if possible) and other

examples of sports equipment such

as a cricket bat or tennis racquet

Teacher’s Notes

See: A Quick Guide to Levers for

additional information.

Education

Teacher’s Notes

The wrist of the hand holding the top

of the ice hockey stick is the fulcrum,

the lower hand provides the effort and

the resistance of object being hit is

the load.

The children may not realise at first that

it is their wrist that is the fulcrum. Their

wrist provides the point of rotation, just

like a door hinge.

 • Introducetheactivitybytellingthechildrentheice

hockey player in the photograph on Page 8 of the

K’NEX Building Instructions needs an improved design

for his hockey stick to help him score more goals. He

knows that he isn’t hitting the puck fast enough but he

is not sure whether he needs to buy a longer or a

shorter hockey stick. The children’s task is to provide

evidence to help him make his decision.

 • TheywillhaveavailableaK’NEXmodelofhisicehockey

stick which they can use to test their ideas.

 • Talkabouthowanicehockeystickisyetanothertype

of lever and that the concepts they learnt in previous

lessons also apply. Review the key points about levers:

  •theyallsharethesamebasicfeatures–arigidbeam

that rotates about a fulcrum, effort and load.

  •whenaheavyobject(load)ispositionedclosetothe

fulcrum, less force (effort) is needed to move it.

Working in Groups of 2-3

 • AskthechildrentofirstbuildtheirK’NEXHockeystick

model, and then investigate, describe and explain how

it works as a lever.

 • UsethephotographonPage8oftheBuilding 

Instructions to observe the position of the

player’s hands.

 • Letthechildrentrythisforthemselvesbyhittingsmall

balls of paper with their K’NEX ice hockey stick.

* Which hand acts as the fulcrum?

* Can you identify exactly which part of that hand

is the fulcrum?

* Which hand provides the effort (the force that

moves the puck)?

* Where is the load?

* The top hand.

* The wrist.

* The lower hand.

* The puck.

Try this:

Working in Groups of 2-3

 • AskonechildtoholdtheirK’NEXicehockeystickand

line it up along the edge of their desktop.

 • Usingonlytheirwrist,theyshouldmovetheicehockey

stick backwards and forwards.

Depending on the flexibility of their

wrists, the head of the ice hockey

stick should move about 4 times

the distance moved by the hand.

Lesson 5: The Ice Hockey Stick

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�5:�The�Ice�Hockey�Stick

 • Theirpartnermarksthestartandstoplinesand

measures the distances moved by the head of the

hockey stick and their partner’s hand.

 • Theirwristmovementisessentiallythesameasadoor

opening on a hinge.

Teacher’s Notes

The fulcrum is the wrist, the effort

is provided by the lower hand on the

stick and the load is the ball of paper

or ice hockey puck.

It remains at rest/stationary until it

is hit with the ice hockey stick. It

then moves away very quickly in the

direction in which it was hit, gradually

slows down and finally stops.

 • Askeachgrouptousedotstickersormaskingtape

to label the positions of the fulcrum (F), load (L) and

effort (E) as well as the direction of the forces involved

(using arrows) on their model.

Whole Class (Optional Activity)

 • Talkaboutwhathappenstotheballofpaperorice

hockey puck before and after it is hit with the stick.

 • Discusstheconceptofbalancedandunbalancedforces.

Ask the children to describe and explain the effect of

balanced and unbalanced forces in this activity.

• Just before the paper ball is hit,

its weight will be balanced by the

reaction of the floor that supports

it. There are no other forces acting

on the paper ball so it remains

stationary until it is hit by the

hockey stick.

• The head of the hockey stick is

moving very quickly when it hits

the paper ball.

• When a force is applied to the

paper ball by the moving hockey

stick, it moves off at a fast speed

but then slows because of friction

between it, the floor and air

resistance. Friction and air

resistance are forces working in

the opposite direction to the

movement of the ball. Why might

a hockey puck move further on

ice than on a floor?

Education

Teacher’s Notes

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

 • Askthechildrentodescribeandexplaintheir

observations. To demonstrate how a hockey stick works

they should use labelled drawings, which include the

positions of the fulcrum, effort and load as well as the

direction of the forces that are applied.

 • Howdothepositionsofthefulcrum,effortandload

compare to the other two examples of levers the

children have investigated?

In 3rd Class levers the effort is

positioned between the load and the

fulcrum. This means that 3rd Class

levers are not as efficient as the other

two lever types because the load will

always be further from the fulcrum

than the effort. As a consequence,

a much larger effort is now needed to

move even a small load.

The main advantage of a 3rd Class

lever is its use in making the load

end move very quickly, as happens

in fishing rods, cricket bats, softball

bats, tennis racquets and golf clubs.

See A Quick Guide to Levers for

additional information on the three

types of levers.

Further information is also available

from the following Internet web sites:

www.howstuffworks.com;

www.enchantedlearning.com/physics/

machines/levers.shtml;

www.flying-pig.co.uk

Working in Groups 2-3

 • Remindthechildrenoftheirdesigntask:Toprovide

evidence to help the hockey player in the photograph on

Page 8 of the Building Instructions decide on the type of

stick he needs to improve his hitting capabilities.

 • Discussthetaskwiththechildrenandaskthemhowthey

will set about their investigation.

  •Howwilltheytesttheirdesigns?

  •Whatwilltheytest?

  •Whatwilltheymeasureandrecord?

  •Howmighttheypresenttheirresultswithreferenceto

the original design specification?

  •Discusstheneedtouseafairtestwithwhichto

evaluate their design ideas.

If the children perform their test by

hand then each test hit may be

different. One possible method to

eliminate the variability in the test

and allow an equal strength hit on

each occasion would be to attach

the K’NEX ice hockey stick to a stand

and allow it to swing from a mea-

sured height. The greater the height

from which the ice hockey stick blade

swings, the harder will be the hit on

the ball.

Ask: Do the test balls all need to be

the same weight? If not, how might

this affect their results? How might they

obtain equally weighted paper balls?

3rd Class Lever

Lesson 5: The Ice Hockey Stick

Education

levers and pulleys

website: www.knexeducation.co.uk

Lesson�5:�The�Ice�Hockey�Stick

Teacher’s Notes

A stationary puck requires the

application of a great amount of

effort (force) in order for it to move

from rest to high speed in a very short

period of time. A longer stick design

makes the head of the stick move

much faster than the player’s hands.

(Think about the radius of a circle.)

A longer hockey stick, however,

may make the control of the head

movement more difficult. Applying

the lever principle: With a longer

hockey stick, the load (the puck) will

be further away from the fulcrum and

it will therefore need more effort

(muscle power) to hit it. A shorter

stick will require less effort and its

movement is more easily controlled.

The trade-off is that the hitting head

will not move as quickly.

That is the designer’s dilemma - how

to make best use of the science.

Extension Activity 1

 • Askthechildrentoinvestigateother3rdClasslevers

used in sports, such as cricket bats, golf clubs,

baseball/softball bats, tennis racquets, and fishing rods.

Provide examples of these pieces of equipment for the

children to examine.

 • Whatdotheplayersneedtobeabletodotomeetthe

objectives of the game? How do the designs of the

different types of sporting equipment meet the needs of

the players?

 • AskthechildrentobuildaK’NEXmodelofthedifferent

types of sporting equipment they have identified and

test their ideas.

Plenary

Share ideas about what makes a good ice hockey stick

design. Ask the groups to report back to the class with

their recommendation to the player. They should make

comments on their designs using the correct technical

and scientific language.

Education

Lesson�6:�Scissors

Connected 1st Class Levers

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

lever, compound, connected,

1st Class levers, pivot, fulcrum,

beam, handles, force, blades,

wedge, object, resistance, design,

specification, compare, labelled,

drawings, shearing, wedges, because,

evaluate, modify, modifications

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Scissors

• Paper and card of different thickness

• Felt-tipped pens

• Modelling clay/Plasticine

You will need:

• Selection of different types of

scissor-like cutting devices. For

example, wire cutters, garden

shears, pliers, and hair-cutting

scissors.

NOTE: These items should be used for

demonstration purposes only. Do not

give these implements to the children.

Possible Teaching and Learning Activities

Introduction

In this lesson the children investigate a familiar tool and

apply their knowledge and understanding of forces when

used in the design of a cutting machine – a pair of scissors.

Whole Class

Demonstrate how scissors can be safely used to cut

paper and textiles.

Demonstrate how the two blades work: the blades cut

across each other in a shearing action.

Teacher’s Notes

A pair of scissors uses two simple

machine concepts in its design: levers

and the wedge. The cutting action

itself is produced by the sharpened

edges of the blades, which are in

fact wedges that work in opposite

directions to each other.

Lesson 6: The Scissors

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�6:�Scissors

Teacher’s Notes

Use a magnifying glass to show

children the shape of the cutting

edge. The role of the levers is to

amplify the squeezing forces from

your hand.

See K’NEX Introducing

Mechanisms: Wheels and Axles and

Inclined Planes Teacher’s Guide for

further work on wedges.

The blades cut with great force

into the paper and, just like all

wedges, move the cut paper edges

apart in a sideways direction. This

action is similar to an axe splitting

wood or a knife cutting an apple

into two pieces.

If possible demonstrate how

this technology works using the

K’NEX wedge model from K’NEX

Introducing Mechanisms: Wheels

and Axles and Inclined Planes kit.

* At the handles.

* The resistance of the paper or

card to the cutting blades.

Some children may observe that

they need to use two effort and

load labels on their model but

only one for the fulcrum. A pair of

scissors makes use of two levers

working in opposite directions and

is an example of compound or

connected 1st Class levers.

The hinge (fulcrum) is common

to both levers and is positioned

between the effort (handles) and

the blades (load).

Working in Groups of 2-3

Investigating how scissors work

 •AllowthechildrentimetomaketheirK’NEXscissors

model and to investigate its action.

* Ask them what scientific concept is being used

when scissors work. You may need to provide

them with a clue. Scissors have a hinge or fulcrum

about which each blade rotates.

* Where is the effort applied?

* What acts as the load?

 •Usedotstickersormaskingtapetolabelthepartsof

the scissors:

F = Fulcrum L = Load E = Effort

Use arrows to show the direction of the applied forces.

Cutting edges of scissors.

The sideways movement of a wedge.

Education

Teacher’s Notes

See A Quick Guide to Levers for

additional information.

You may find it useful to draw a

diagram on the board to illustrate

this arrangement.

 •Askeachgrouphowtheymighttestthescissors’

cutting action? Fingers are NOT allowed, even

with plastic.

 •Whereisthestrongestcuttingactionfound?

 •Whereistheweakestcuttingactionfound?

 •Askthechildrentodescribeandexplainverballyand

in written text, how their K’NEX scissors work. They

should be encouraged to use labelled drawings

indicating the positions of the fulcrum, effort and

load and the direction of the applied forces.

Whole Class

 •Showthechildrenaselectionofotherscissor-like

cutting tools with which they may be familiar and which

have a similar cutting action to scissors.

 •Discusshowallthecuttingtoolshavethesamebasic

design but that the design has been modified to make

each of them meet different needs.

  •Foreachcuttingtoolinturnask:

  •Whattypesofmaterialisthistooldesignedtocut?

  •Wouldscissorsbeabletocutthesematerials?

If not, why not?

  •Howdoesthedesignofthiscuttingtoolallowitto

cut materials that scissors cannot?

  •Askthechildrentomakelabelleddrawingsofthe

different types of cutting tools, indicating the position

of the fulcrum, effort and load. They should make

short notes to describe how the design of the cutting

tool fits them for the jobs for which they are used.

You might suggest using thin

rolls of modelling clay/Plasticine

and use the indentation made by

the cutting blades as a possible

measure of the cutting forces

made by the blades.

To promote the wider use and

application of ICT skills and

practices, the children’s models

and work might be recorded using

a digital camera.

Cutting tools with short blades

and long handles are used to cut

difficult materials such as wire or

thick branches. The long handles

help amplify the squeezing force

(effort), while the short blades mean

that the load, or resistance, is near

the fulcrum or hinge. This posi-

tion is where the cutting forces are

greatest. Remind the children about

their investigations when using their

K’NEX scissors to cut modelling

clay.

Hair cutting scissors, on the other

hand, have long blades and short

handles because the main need is

to make long straight cuts. You do

not need a lot of cutting force to

cut through hair.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 6: The Scissors

Education

Lesson�6:�Scissors�

Teacher’s Notes

To promote the wider use and

application of ICT skills and

practices, the children’s models

and work might be recorded using

a digital camera.

Design Task

Ask the children to modify the design of their K’NEX scis-

sors model so that it has a much stronger cutting or gripping

action. With the aid of a labelled drawing of their design,

they should write a description of how their design works

and state how their modifications have made the cutting

action stronger. They should also include the results of any

tests they carried out.

Extension Activity 1

If time is available the children might be asked to transfer

theirdesignintoresistantmaterials.Youmightaskthem,

for example, to make a pair of tongs from wood and other

appropriate materials that can pick up and hold an object

weighing 200g or more. What is the greatest weight their

tongs can lift?

Plenary

Select some models to share with the class and ask the

children to describe:

 •Thereasonsbehindtheirdesign.“Wedidthis 

because…”

 •Whytheirdesignworksbetterthattheoriginalmodel.

 •Thepartsoftheirdesignthatpleasethem.

 •Whatteststheycarriedouttoevaluatetheirdesign

against the design brief.

Education

A�Quick�Guide�to�Pulleys

A pulley is a very simple type of mechanism;

it has been used for thousands of years to

make easier the job of lifting heavy objects.

The simplest type of pulley mechanism is a

single pulley.

When a single pulley is used as a lifting device,

the effort force needed to raise the load must

be equal to or just greater than the load. In

theory the effort needed to lift the load is the

same as if the load was lifted directly from

the ground without using a pulley. In prac-

tice, however, the effort force must be greater

than that of the load in order to overcome the

added effects of friction in the system.

Key elements of a pulley mechanism

 • Pulley

- a freely revolving wheel with a

groove in its outer rim through which a

rope, cable or chain can be passed.

 • Effort – the pulling force applied to the

rope to lift the load.

 • Load – the weight of the object to be

moved by the effort force.

One way of getting bricks to the top of a

building is to pull them vertically upwards. This

method requires a great amount of hard work.

Using a single pulley mechanism, however,

allows heavy objects to be lifted by pulling

down on a rope from below. This is an easier

and safer way to raise the load of bricks than

to be on the roof pulling them up. So how

does it work?

What is a pulley?

A pulley is a mechanism that can change the

direction of an effort, or pulling force, applied

to a rope. This means that a pull down may

be converted into a pull up. Pulleys can also

be used to amplify the applied effort force.

Passing a rope over the rim of a revolving

wheel or pulley helps to reduce the amount

of friction in the system.

A Quick Guide to Pulleys

What can pulleys be used for?

Pulleys can:

 • Changethedirectionoftheapplied

effort force

1. A downward pull on the rope running

over a single fixed pulley results in an

upward movement of the load.

levers and pulleys

website: www.knexeducation.co.uk

Education

2. Pulleys can also be used to move

loads horizontally using a vertically

applied effort force. A downward pull

on a rope attached to a pulley system,

can move a clothesline horizontally.

Multiple pulleys and cables are found in

systems used to lift very heavy loads. A

multiple or compound pulley system is

called a block and tackle. Using multiple

pulleys amplifies the effort force still fur

ther so making the job of raising the very

heavy loads easier to do.

Why is it called a block and tackle? The

block is the frame that holds the pulleys

and the tackle is the rope or cable.

 • Amplifytheappliedeffortforce

As more pulleys are used in a pulley

system, less effort is needed to move or

lift a load, but a longer amount of rope

must be pulled through the system. This

is the trade-off. Less effort is needed

but it is applied over a longer distance.

For example, in a system composed of 2

pulleys – one upper pulley that is fixed

and one lower, movable pulley – you only

need apply half the effort force that would

otherwise be needed to raise the load if

pulleys were not used. The distance you

must pull the rope, however, will be dou

ble the distance moved by the load.

Sailboats and yachts make much use of

these types of pulley systems to handle

and control large heavy sails.

A�Quick�Guide�to�Pulleys

Education

levers and pulleys

website: www.knexeducation.co.uk

A Quick Guide to Pulleys

Key facts about pulleys:

Single or fixed pulley

Examples: flagpole, clothesline, painter’s platform.

A single fixed pulley must be attached to a

frame and the pulley wheel can rotate freely to

reduce friction.

Fixed pulleys change the direction of the

applied effort force.

The load moves the same distance as the

effort force.

Using a fixed pulley, however, enables you pull

down and to use gravity to your advantage by

allowing you to add your body weight to the

effort made by your arm muscles, so making it

appear to be easier to lift the load.

When a single pulley is used as a lifting device,

the effort force needed to raise the load must

be equal to or just greater than the load. In

theory the effort needed is the same as if the

load was lifted directly from the ground. In

practice, however, the effort has to be greater

than the load in order to overcome friction in

the pulley system. Using a rotating wheel is

one way of reducing friction.

Movable Pulleys

When two pulleys are used, the upper pulley

must be fixed to a frame while the lower

movable pulley is attached to the load it lifts.

The two pulleys are connected by a single

continuous rope and when the rope is pulled

down, the lower pulley moves upwards taking

the attached load with it.

Fig. 1

The advantage of a pulley can be seen

when you compare using a fixed pulley to

lifting from above. When lifting from above

you can only use muscle power to pull the

load upwards, all the time working hard to

overcome the effects of gravity.

Fig. 2

Movable pulleys amplify the applied effort

force. As more pulleys are used, less effort is

needed to raise the load, but the rope must

be pulled through a greater distance.

Education

A�Quick�Guide�to�Pulleys

In the example shown in Fig. 2, two pulleys

are used. The weight of the load being raised

is distributed equally between the two parts of

the rope on either side of the movable pulley.

The force needed to hold the system in

balance or to raise it is now only half that of

the load. The downside is that the effort force

must move twice as far as the load. For

example, to lift a 20N load a height of 3cm.

the 10N effort force must move a distance

of 6cm.

Compound Pulleys

Compound pulleys are made from two or

more sets of pulleys connected by the same

rope. The upper set is made from fixed pul-

leys attached to a frame, while the lower

set is made from movable pulleys. Effort is

applied by pulling down on the rope or chain.

Compound pulleys not only change the

direction of the applied force but they also

increase the force applied to the load.

As more pulleys are used, less and less effort

is needed to lift heavy loads. In Fig. 3, the

K’NEX block and tackle model has 4 strings

supporting the two lower movable pulleys.

The number of supporting strings equals the

number of times the pulley system multiplies

the effort force.

If the load to be lifted by the K’NEX block

and tackle model is 4N, then the effort force

required to lift it will be 1N. This is because the

load is divided between four parts of the rope,

each part carrying a quarter of the load.

If the load is raised 1cm, the cumulative effect

on the distance moved by the effort will be 4

x 1cm. In this example the effort will move 4

times the distance moved by the load.

Fig. 3

Education

Lesson 7: The Flagpole

Lesson�7:�The�Flagpole

A Fixed Pulley System

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •pulleysarewheelswithgroovesaroundtheirouterrim

 •pulleyscanbeusedtoliftobjectsandchangethe

direction of movement

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

pulley, wheel, groove, rim, fixed, pull,

force, lift, raise, lower, gravity, rotary,

motion, linear, load, effort, Newtons,

measurement, opposite, direction

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Measuring tape or rulers

• Coloured paper or cloth

• Coloured crayons or pencils

• Scissors

• Stapler, glue or tape

• 200g slotted weights

• 1 small bucket or basket filled with

heavy objects

• String/rope

• Broom handle

Possible Teaching and Learning Activities

Introduction

The activities in this lesson may be used to support the

QCA/DfEE Exemplar Scheme of Work for:

Design and Technology Unit

•2C:WindingUp

Science Units

•1E:PushesandPulls

    •2C:ForcesandMovement

    •6E:BalancedandUnbalancedForces

Whole Class/Demonstration:

 • Reviewwiththechildrenhowmanyofthesimple 

machines they have investigated make it easier to lift

heavy objects.

 • Askforavolunteer(s)tobend,facedown,overa 

table/desk, next to one edge, and reach down on the

side of the table/desk to lift a bucket or basket filled

with heavy objects. (Children should not extend an arm

over the front of the desk).

 • Askthevolunteertodescribehowdifficult(oreasy)

this was for them.

 • Securearopetothebucketandaskthemtopullitup

using the rope.

 • Encouragethechildrentoconsiderwaysinwhichthis

could be done more easily. For example: place a broom

handle across two desks and loop the rope over the

handle. The volunteer can now pull down on the rope

instead of pulling up. Does this arrangement make it

easier or more difficult to lift the load? Record their

suggestions/answers on the board for later reference

and discussion.

 • Explainthattheirtaskistobuildamodelthatwill 

demonstrate the use of a simple machine called a

pulley that can make the job of raising an object easier.

levers and pulleys

website: www.knexeducation.co.uk

Education

Working in Groups of 2-3

 • AskthechildrentobuildtheK’NEXFlagpolemodel,

(Pages 10-11 of the Building Instructions booklet), and

allow them time to investigate how it works and what

it does.

 • Withthehelpofalabelleddiagramdrawnontheboard,

discuss how a pulley wheel works and how the rope fits

into the groove in the rim of the wheel.

Whole Class

 • ExplainhowtheirK’NEXFlagpolemodelprovidesan

example of a FIXED pulley. This is a pulley that does not

move when the rope is pulled, although the wheel may

spin in place.

 • Askthechildrenwhytheythinkflagpolesmakeuseof

pulleys to raise and lower a flag.

 • Howwouldtheygetaflagtothetopofthepoleifthey

did not use a pulley?

 • Wherehavethechildrenseenotherexamplesofthis

type of pulley being used?

Teacher’s Notes

The children should not cut the

string in this model. A long string

will be needed for subsequent pulley

building activities.

See: A Quick Guide to Pulleys and

Key Technical Terms and Scientific

Definitions for additional information.

It is easier and safer to pull down on a

rope to raise a flag than it is to climb a

tall ladder to secure the flag to the top

of the pole.

Possibly on cranes, washing lines,

on equipment in the school gym,

or classrooms.

Free photographs of pulleys in

action on cranes can be obtained from

www.freefoto.com

How many different types of machines do the children know

about that use pulleys in their mechanisms?

What do these machines do?

A pulley is a wheel with a groove

around its outside edge into which a

rope or belt can fit. By pulling down

on one end of the rope a load on the

other end can be lifted. Pulleys can

be used to change the direction of

movement and can make it easier to

lift heavy objects. Children will be

able to explore different types of pulley

systems during the next few lessons.

For additional information please

refer to A Quick Guide to Pulleys and

Key Technical Terms and Scientific

Definitions.

Internet Web site on pulleys:

www.howstuffworks.com and

search ‘pulleys’.

Lesson�7:�The�Flagpole

Education

* Amplifying forces to help lift

  heavyobjectsusinglittleeffort.

* The circular motion of a

motor is transferred to wheels

or cylinders.

* Changing the direction

of movement.

Some examples you may want to discuss with the

children include:

* liftingheavyobjects,asincranesorrunningaflag

up a flagpole.

* transferring movement and forces in sewing

machines and vacuum cleaners.

* moving equipment in the gym or even opening

and closing curtains.

NOTE: Care should be taken when pulling down on the

string so it does not slip. The string should be grasped just

belowthepulleyandpulleddownSLOWLY.

 • Doesthepulleymakeliftingthemasseasier?

* What types of movement are produced by

pulley systems?

* (i) Linear: by the moving load

and the pulling force.

(ii) Rotary: by the pulley wheel.

Working in Groups of 2-3

(If the children have added the string to their flagpole, ask

them to remove it before beginning this next activity.)

 • Askthechildrentocompletethefollowing:

Step 1: Attach a slotted mass to one end of the string

and simply lift it vertically by hand. Ask them to feel how

much force or effort is needed to lift the mass. What

happens when they let go of the string?

Step 2: Pass the string over the pulley. Lift the mass by

pulling the string. Feel how much force is now needed to

lift the mass.

The pulling force is the effort, while

the mass being lifted is the load. This

is the same as in levers. When using

the fixed pulley the children pull down

on the string to raise the mass. It is

easier to pull down on the string using

a pulley because “body” weight can

also be used to help the pulling

forces. (Ask them to remember the

demonstration at the beginning of the

lesson when a pupil reached down

to lift up a heavy load.) When pulling

directly upwards only “muscle” power

can be used. In fact, the same amount

of effort is used in both cases.

• Askthechildrentousestickerstolabelthefixedpulley

and the directions of movements of the effort and load.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 7: The Flagpole

Education

Lesson�7:�The�Flagpole

• Howmightthechildrenmeasuretheforcesneeded?

Teacher’s Notes

A force meter could also be used for

these activities to enable the children

to take direct measurements. If you

have not already done so, demonstrate

how a force meter is used to measure

forces and explain that the unit of mea-

surement is Newtons (N).

Step 3: Ask the children to repeat Step 2 but only this

time they should measure the distances moved by their

hand (the effort) when pulling on the string and the

distance moved by the mass (the load). One child should

grip the string just below the pulley and pull down slowly

to lift the load. Another child then measures:

(i) how far the string has been pulled

(ii) how far the load has been raised above the desktop.

 • Whatdotheirmeasurementstellthemabouthowa

fixed pulley works?

To lift a load the children would have to

pull on the rope with at least as much

force as the weight of the load. They

might test this by connecting a force

meter to either end of the pulley rope,

pulling each force meter and recording

the reading.

The distance moved by the effort and

the load is the same. If force meters

have been used then, in theory, the

values obtained for the effort force and

load should also be the same. In reality,

however, the effort force is likely to be

larger because of the additional effect

of friction in the pulley system. Fixed

pulleys only change the direction of

movement or the applied force; they

do not amplify the force.

 • Askeachgrouptorecordandexplaintheirfindingsand

observations by writing and making labelled drawings.

They should indicate the direction of the applied forces,

the direction of movement of the pulling force and the

object being raised. The children should be encouraged

to use the correct scientific vocabulary.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

Teacher’s Notes

When the load is pulled upwards,

the pulling force is greater than the

weight of the object – the forces are

unbalanced. When the object is held

still, the forces are balanced – it is

not moving. The force applied on the

rope end equals that of the weight on

the other end. When released it falls

because there is now no upward pull-

ing force but only the force of

gravity pulling it downwards.

Optional Activity for Step 3

 • Askthechildrentodescribewhattheyhaveobserved

in terms of balanced and unbalanced forces.

Education

Extension Activity 1

Working in Groups of 2-3

 • Askthechildrentodesignaflagfortheirflagpoleusing

coloured paper or cloth, felt-tipped pens or crayons.

 • Howaretheygoingtoattachtheirflagtothestringso

that it is also easy to remove?

 • Howcantheymakesuretheflagcanopeninabreeze?

Alternative activity

Working in Groups of 2-3

Design a flag code message system to be used to send and

receive short secret messages to and from another group.

Plenary

Discuss what the children have learnt about pulleys and how

they are used, using vocabulary that relates to the science

and technology they discovered.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

If possible, retain a flagpole model, with

its fixed pulley, so that the children can

compare it with the compound pulley

system used in the sailboat model.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 7: The Flagpole

Education

Lesson�8:�The�Sailboat��

A Compound Pulley System

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

pulleys, fixed, movable, force,

effort, load, double pulley sys-

tem, single pulley system, com-

pound, compare, doubled, amplify,

because, trade-off, pull, force

meter, prototype, Newton, friction,

lift, lower, raise

Possible Teaching and Learning Activities

Introduction

Whole class

 •Reviewwiththechildrenhowtheuseofapulleysystem

helps make the job of raising a flag to the top of a pole

easier. In this case, the pulley is used to change the

direction of the effort force – it is easier to pull down on

a rope than to pull up on one. Using a pulley system

also means that you do not have to climb a ladder to

reach the top of the pole.

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Introduction to Simple

Machines: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Measuring tape or rulers

• Coloured paper or cloth

• Coloured crayons or pencils

• Scissors

• Stapler, glue or tape

• 200g slotted masses or

5 Newton force meter

• Large paperclips

You will need:

• The K’NEX flagpole model

• Pictures of sailboats and sailing

ships available for the children

to view

• Additional lengths of string for

Extension Activity 2 (optional)

Teacher’s Notes

More information on pulleys is

available from A Quick Guide to

Pulleys and the Internet web site

www.howstuffworks.com

Education

Teacher’s Notes

Free photographs can be obtained

from www.freefoto.com and http://pics.

tech4learning.com/

 • Askthechildrentolookatthepicturesofdifferent

sailing boats. Talk about how, regardless of the size of

the sailboat, sailors have always been faced with the

same problem: how to lower and raise heavy sails

safely. In days of large sailing ships sailors had to

climb the masts and literally pull up large, heavy

sails by hand – it was very dangerous work. Modern

sailboats use pulley systems that allow the crew to

raise and lower sails quickly without leaving the

(relative) safety of the deck.

 • Thislessoninvestigateshowpulleyscanbeusedto

lift heavy objects.

 • Askthechildrentocollect/findpicturesoflifting 

machines from books or from research using

the Internet.

 • Discusshowpulleyscanbeusedinanumber

of situations.

 • Allowthechildrentimetoinvestigatephotographsor

illustrations of lifting machines that use pulleys.

 • Whatarethesemachinesusedfor?

 • Howheavyaretheloadstheylift?

 • Isthereanyconnectionbetweenthesizeoftheloads

and the number of pulleys and ropes/cables they use?

Working in Groups of 2-3

 • AskthechildrentoconstructtheK’NEXSailboat

model shown on Pages 12-13 of the Building

Instructions booklet.

Building Tip: Building Steps 6 – 8 will require cooperation

between the members of the group. This applies particularly

to Step 7 when string is attached to the pulleys. Make

sure that one child holds the movable pulley (built in Step 6)

while another carefully threads the string around the

pulley wheels.

Remind the children that they should NOT cut the

string. They will need a long string for several other

pulley activities.

 • Allowtimeforthechildrentoinvestigatehowthesail

mechanism works by lifting a mass attached to the

lower pulley. An opened, large paperclip could be used

as a hook.

Talk about how machines that are

used to lift heavy weights usually

have numerous pulleys in the lifting

mechanisms. The greater the number

of pulleys that are used, the easier it

becomes to lift heavy loads.

In this model pulley system there are

two pulleys, an upper fixed pulley and

a lower movable pulley. Two ropes are

attached to the lower movable pulley.

This arrangement is called a double,

or compound, pulley system.

Fixed pulley

Movable pulley

Lesson 8: The Sailboat

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�8:�The�Sailboat

 •Askthechildrentoconsiderhowthelowerpulleydiffers

from the pulley wheels at the top of the mast. Talk about

the concept of movable pulleys.

 •Whatdotheynoticeaboutthedistancesmovedbythe

lower pulley wheel and the end of the rope? Are they the

same as in the flagpole model, or different? If possible,

have the flagpole model available for comparison.

 •Whatdotheynoticeabouttheeffortforcesneeded

to pull the string to raise the load? How do their

findings compare with what they found using the

flagpole model?

 •Usestickerstoidentifyandlabelthefixed and

movable pulleys and the directions of movement

observed.

 •Askthechildrenhowtheymighttesthowwelltheir

pulley system works? Discuss how they might measure

the forces used? How many measurements do they

need to take?

 • Askeachgrouptorecordandexplaintheirfindings

and observations through writing and labelled

drawings. They should indicate the direction of the

applied forces, the direction of movement of the pulling

force and the object being raised. The children should

be encouraged to use correct scientific vocabulary.

Teacher’s Notes

The distance moved by the effort

or pulling force - the child’s hand

pulling the string – is twice that

moved by the load but the pulling

force needed to move the load

is halved.

This is the trade-off. The pulling

force (effort) needed is halved

but the distance it has to move

is doubled.

It may be necessary to review that

forces are measured in Newtons

(N) and if weights are used, how

their values can be converted into

Newtons. Alternatively, two force

meters may be used - one to

measure the downward pulling

force and the other the force that

is to be overcome.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

Education

Extension Activity 1

Working in Groups of 2-3

If time is available, ask the children to design a sail for their

sailboat using appropriate materials. The children could use

photographs of sailboats to research ideas for sail designs

and shapes.

 • Howwillthesailbeattachedtotheirmechanismfor

raising and lowering?

 • Howwillthesailbe‘fixed’inpositionwhenithas

been raised?

Extension Activity 2

Design Task - Working in Groups of 2-3

Their sailboat needs to be rigged for use by a crew with

physical disabilities. The task is to design a sail handling

system to raise and lower two sails, one fore and one aft,

which can be operated from the deck.

They can only use the contents of the kit to make

their prototype.

Allow the children time to select, measure and make a sail

from suitable textiles.

 • Howwilltheyattachthesailto

(i) the raising mechanism

(ii) the sail boom?

 • Howdorealsailboatsdothis?

 • Cantheymakeuseofthe“flagpole”mechanism?

The children should be encouraged to draw plans for their

design, indicating how they think it will work.

On completion ask:

 • Whatchangesdidyoumakeduringthetestingof

your design?

 • Whatwerethemostdifficultpartstomake?

 • Howdidyousolvetheproblems?

Plenary

Review what the children have learnt about movable and

fixed pulleys and how, when fixed and movable pulleys

work together, they form a compound pulley system.

Note: The “rope” that comes with the

kit should not be cut, so an alternative

will be necessary.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 8: The Sailboat

Education

Time: 1 - 1.5 hours

LearningObjectives - Children should learn:

 •toobserveanddescribemovementsinasimplemachine

 •torelatesciencetothewaysinwhichfamiliar

machines work

 •tocarryoutasimpleinvestigation

Vocabulary

block and tackle, pull, pulley,

fixed, movable, force, effort, load,

counterbalance, counterweight,

balanced, unbalanced, lever,

modify, evaluate, amplify, trade-off,

topple, unstable, stability, compare,

because

Possible Teaching and Learning Activities

Introduction

Whole class

 •Discussand/orreviewthechildren’sprevious

experiences in which they discovered a connection

between the number of pulleys used in a pulley system

and the amplification of the pulling force – the greater

the number of pulleys used, the easier becomes the

lifting job.

 •Show,oraskthechildrentofind,photographsand

pictures of cranes at work.

 •Askthemtodescribethepulleyssystemstheyuseand

the jobs they have to do?

 •Howdotheythinkthesepulleyssystemsmakeiteasier

to lift heavy loads?

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Introduction to Simple

Machines: Levers and Pulleys kit

with Building Instructions booklet

• Dot stickers or pieces of masking

tape

• Felt-tipped pens

• Measuring tape or rulers

• Paper cup

• 200g slotted masses

• Large paperclips

• 2 x 5 Newton force meters (optional)

Teacher’s Notes

Photographs of cranes can be

obtained from www.freefoto.com.

and http://pics.tech4learning.com/

www.freefoto.com has some

good photographs of a giant float-

ing crane pulling the Gateshead

Millennium Bridge in place.

Internet research:

www.howstuffworks.com.

For additional information on

pulleys see A Quick Guide

to Pulleys.

Lesson�9:�The�Block�and�Tackle�

A Compound Pulley System

Education

Teacher’s Notes

The correct answer is 4 times.

The multiplication can be found by

counting the number of lengths of rope

supporting the movable pulleys. In

this example there are 2 movable

pulleys, each with two supporting

ropes = 4. (The three pulleys at the

top of the structure are fixed pulleys.)

See: A Quick Guide to Pulleys.

Whole class

 • Introducetheactivitiesbyexplaininghowthecranes

use ‘block and tackle’ mechanisms to lift very heavy

loads and how a block and tackle can make the job

of lifting heavy objects easier.

 • BeforebuildingtheirK’NEXBlockandTacklemodel

ask the children to look at the plans for their model on

Page 15 of the Building Instructions booklet.

 • Explainhowtheblockandtackleisconstructedby

winding the rope around a number of fixed and

movable pulley wheels.

 • Howmanytimesdotheythinktheliftingforcewillbe

increased by this pulley system?

Working in Groups of 2-3

Let’s Investigate

 • AskthechildrentoconstructtheirK’NEXBlockand

Tackle model and allow them some time to investigate

how it works.

 • Askeachgrouptoidentifyandlabelthefixedand 

movable pulleys in their model.

 • Howdothechildrenthinkusinganumberoffixedand

movable pulleys in a lifting mechanism will affect its

ability to lift a load?

 • Askeachchildinturntoplaceapapercupcontaining

one or more 200g masses on the palm of his or her

hand and to raise and lower it. This will allow them to

gain some impression of the load being lifted by their

model and the forces needed to raise it.

 • Suggestthechildrentryliftingthepapercupusingthe

K’NEX Block and Tackle model.

  •Askwhathappenedtotheirmodelwhentheyfirst

tried to lift the weighted paper cup?

  •Askthechildrentoexplaintheirobservations.

  •Whatotherscienceconceptisworkinghere?

  •Howmighttheysolvetheproblem?

Force meters could be used to

record the actual forces needed to

lift the weighted paper cup vertically.

These can then be compared with

those needed when using the block

and tackle.

The K’NEX Block and Tackle model

becomes unstable and will topple

forwards as the weighted paper cup

is lifted. When the load is lifted off the

desktop the structure acts like a lever

that pivots around its front edge. The

front edge becomes the fulcrum and

if the weight of the load is greater than

the weight of the model, the model

will topple in the direction of the load.

The forces in the system have

become unbalanced.

A counterweight is needed to balance

the weight of the load being lifted.

The folder shown in the photograph

on Page 15 of the Building Instructions

booklet is acting as the counterweight.

Lesson 9: The Block and Tackle

levers and pulleys

website: www.knexeducation.co.uk

Education

Lesson�9:�The�Block�and�Tackle�

In cranes the counterweight is very

heavy because it must be placed

close to the fulcrum. Ask the children

to identify the positions of the

counterweights in the photographs

of cranes they have found.

Teacher’s notes:

Investigating Further

There are two approaches you might

consider using:

a) Building on earlier lessons, ask

the children to plan their own tests,

including measurements to be

taken and data logging techniques.

Children could use rulers and

measuring tapes to measure the

distance moved by the effort and

load. Force meters could be used

to record the effort force.

(b) Directed investigation

 • Askthechildrentoplacetheweightedcupinthebasket

and pull on the string to lift it.

b) Direct the children as to what they

should do.

Investigating Further

 • Explainthatastheyusetheblockandtacklemodelto

lift a load the children should try to discover answers

to the following questions:

  •Whatdidtheyfindoutabouttheamountofeffort

needed to lift the load?

  •Howdoesthelifting‘power’ofthismodelcompare

to the other pulley models?

  •Howdoesthepulleysysteminthismodeldifferfrom

the other pulley models they have investigated?

(a) Planning their own tests

 • Askthechildrenhowwilltheytesttheirideas.

 • Encouragethemtoplanandexplaintheirtestsbefore

carrying them out.

 • Whatmeasurementsdotheyneedtomake?

How will they take their measurements?

 • Howwilltheyrecordtheirresults?Inatable?

 • Referthembacktowhattheydidinearlierlessons

on pulleys.

Education

Teacher’s Notes

Force meters could be used to

compare the actual forces needed

to lift the weighted paper cup verti-

cally with those needed when using the

K’NEX block and tackle model.

An alternative approach could be

to use two force meters - one

representing the pulling force, or

effort, and the other the load to

be overcome by the effort.

 • Feeltheforceneededtolifttheweightedpapercup.

 • Howdoesliftingtheweightedpapercupwiththeblock

and tackle compare to lifting it directly by hand?

 • Countthenumberofstringssupportingthelower 

movable pulleys. What might this information tell you

about how much this block and tackle system helps

you to lift the load?

 • Usingtheblockandtackle,raisethecupabout5cm.

Measure how far the string must be pulled to allow the

paper cup to reach this height?

For either approach:

 • Askthechildrentodescribeandexplaintheir

observations, to make labelled drawings of their model

and use arrows to indicate movements. They should be

encouraged to use the correct terminology to describe

the different components.

Extension Activity 1

Design Task

Working in Groups of 2-3

The present lifting mechanism is not safe when in use.

Modify the design so that it will not topple when lifting

heavy objects.

The children should be encouraged to

(i) draw plans for their design

(ii) explain how they will evaluate it

(iii) write a description of how they think it will work.

On completion ask:

  •Whatchangesdidyoumakeduringthetestingof

your design?

  •Whatwerethemostdifficultpartstomake?

  •Howdidyousolvetheproblems?

The children should notice a significant

reduction in the effort needed to lift the

weighted cup when using the block

and tackle. They should also observe

that there are 4 strings supporting

the two lower movable pulleys. This

system makes it 4 times easier to lift

the weighted paper cup load, but the

‘trade-off’ is they have to pull the string

4 times the distance moved by

the load.

To promote the wider use and

application of ICT skills and practices,

the children’s models and work might

be recorded using a digital camera.

Extension Activity 2

Design Task

Working in Groups of 2-3

Yourmotherisaphysicaltherapistworkingwithpeople

who have been injured and have to use wheelchairs. It is

often difficult for your mother to lift the patients out of their

wheelchairs to use the machines for their exercises. Using

K’NEX and other appropriate materials, design and make

a portable pulley system that can lift patients out of their

wheel chairs and transport them to the different exercise

machines. Explain how your machine operates and how it

uses pulleys to accomplish the task.

levers and pulleys

website: www.knexeducation.co.uk

Lesson 9: The Block and Tackle

Education

Lesson�9:�The�Block�and�Tackle�

Plenary

Discuss what the children have learnt in the lesson

using the words relating to the science and technology

they discovered.

Ask them what they think the effect of adding more pulleys

to their block and tackle might be on its lifting ability.

Talk about patterns that may be arising in their results

fromthisandotherlessons.Youmaywanttodiscuss,for

example, how simple machines help to make jobs easier

to do by increasing/amplifying applied forces, but note that

there is a trade-off. Using a simple machine can mean that

they expend less effort BUT they have to apply the effort

over a longer distance.

Education

This list of key terms is intended as background information.

While we recognize that some of these terms are not fundamental

to National Curriculum requirements for Key Stage 2 Design and

Technology and Science, we have nevertheless included them here

to help you better understand some of the concepts investigated in

the K’NEX Understanding Mechanisms kits.

SIMPLE MACHINE

A simple tool used to make jobs easier to do. For example, a lever allows you to apply a

small force to move a much larger load. Try pulling a nail out of a piece of wood without a

claw hammer. A claw hammer uses the lever principle in its design. Other examples of simple

machines are wheels and axles, pulleys, inclined planes or ramps, wedges, and screws.

Simple machines can be used to increase forces or change the direction of a force needed to

make an object move. They are simple because they transfer energy in a single movement.

Simple machines make it easier for you to do jobs by changing the way in which jobs can be

done; they cannot change the job to be done. For example, you can load a heavy object onto

the back of a lorry by lifting it the short vertical distance – a process that will require a lot of

effort. Alternatively, you can take the take the longer but easier route up a ramp with the object.

Either way, the job is done.

In science, when an object is moved by a force work is said to have been done. Simple

machines make it easier for you to do work. Some simple machines allow a small force to

move a large load and are called force amplifiers. For example: crowbars and wheelbarrows.

Other simple machines can be used to convert small, slow movements into large, faster

movements. Such machines are distance or speed amplifiers. A fishing rod used to cast a

hook, or a mediaeval throwing machine, such as a trebuchet, are examples of this application.

COMPOUND MACHINES

These have two or more simple machines working together in their mechanism. For example,

two 1st Class levers make up a pair of scissors, or pliers, while a complex car engine may be

made from several hundred mechanisms.

WORK

Work is a scientific concept and is only done when a force moves an object in the same

direction as the applied force.

If you push against an object and it does not move then, from a scientific point of view, you

will not have done any work. For example, no matter how hard you push in an attempt to

move a car while its brakes are on, you will have not done any work if it has not moved. Once,

however, the brakes have been released and the car starts to move, then you will be doing

work. The amount of work you do depends on the magnitude of the force you apply and the

distance you move the object.

Key Terms and Scientific Definitions

Key�Technical�Terms��

and�Scientific�Definitions

levers and pulleys

website: www.knexeducation.co.uk

Education

Work=ForcexDistancemovedbytheobjectinthedirectionoftheforce

W = F x d

If the force is measured in newtons (symbol N) and the distance is in metres (m) then the

work done (W) is measured in newton metres (Nm).

The SI unit of work is the joule (J) and 1joule=1newtonmetre.

FORCE

A force is a push or a pull which, when applied to an object, can make it change shape, move

fasterorslower,orchangedirection.Youcannotseeforcesbutyoucanfeelorseetheir

effects.

A force has both size and direction. The size of a force is measured in newtons (N) and can be

measured using spring balances called force meters or Newton meters.

EFFORT

The force you apply to move one part of a simple machine, i.e. the input force that is applied

to a simple machine, or mechanism, to make it do work. With a wheel and axle simple machine,

the effort force can be applied to either the wheel, or the axle, in order to make the other part

move. Think of a waterwheel being turned by a millstream or a car axle driving the road wheels.

The function of a simple machine, or mechanism, is to transfer the force both to the location

and in the direction in which it is needed to move the load.

LOAD

The weight of an object to be moved or the resistance that must be overcome before an

object can be moved.

The resistance can be the frictional forces in a mechanism itself or simply the friction between

two surfaces.

RESISTANCE

The force that works against the effort. It could be either the weight of the object to be moved

and/or frictional forces.

FRICTION

The force that occurs when two surfaces rub against each other. Friction tends to slow things

down, which means it can be both beneficial and unhelpful. For example: friction is beneficial in

the case of brakes applied to the wheels of cars and bicycles to slow them down, but friction

between surfaces can also cause wear - tyres wear out. Rough surfaces increase friction, while

smooth surfaces reduce it.

Frictionalsogeneratesheat.Youcanfeelthiswhenyourubyourhandstogetherquickly.

Key�Technical�Terms��

and�Scientific�Definitions

Education

Key Terms and Scientific Definitions

levers and pulleys

website: www.knexeducation.co.uk

MECHANICAL ADVANTAGE

Most machines are designed to make jobs easier to do. For example, a wheelbarrow that

allows you to move a heavy load of soil or a winch used to lift a heavy object. When a

machine enables you to use a small effort to move a large load, that machine has given you

a “mechanical advantage” you would not otherwise have had. How large or small a mechanical

advantage a machine provides can be measured by comparing the load you can move with

the effort you used to move it.

The calculation used is:

The mathematical calculation indicates how many times the machine multiplies the effort force.

For example, if a machine allowed you to move a load of 300N using a 100N effort force, the

mechanical advantage of the machine will be 3:1 or simply 3.

If the value of the MA is greater than 1 then your machine allows you to move a large load using

an effort force less than that of the load. Does this mean you can get something for nothing?

Can you get more from less? Unfortunately this is not the case. While a high MA value means

you can use less effort force than that of the load to be moved, the distance moved by the effort

will be much greater than that moved by the load. This is the trade-off.

Remember, simple machines and mechanisms can make it easier to do a job by changing

the way in which the job is done; they do not change the actual job to be done. The work

needed to be done will always remain the same, so that to move a load, you can use a large

effort applied over a short distance, or a small effort applied over a longer distance. It all

balances out in the end.

MECHANISMS

Although designed and made to do different jobs and make jobs easier to do, all mechanisms

share some common features.

 •Theyaremadefromsimplemachines,eitherusedsinglyorincombination.

 •Theyinvolvesomeformofmotion.

 •Theyneedaninputforcetomakethemwork.

 •Theyproduceanoutputforceandmotionofsomekind.

Mechanical Advantage (MA) = Load

Effort

Education

Key�Technical�Terms��

and�Scientific�Definitions

One form of motion (input) can be converted into another (output) through the use of

a mechanism (process).

TYPES OF SIMPLE MACHINES

 •Lever: A rigid beam, bar or rod that turns, or rotates, about a fixed point called the

fulcrum. For example: a child’s seesaw.

 •Wheelandaxle: A round disk (wheel) with a rod (axle) rigidly connected through the

centre of the wheel so that they both turn together. A wheel can be used to turn an axle

or an axle can be used to turn a wheel. For example: a winch raising a bucket from a well.

The wheel can be a solid, circular disk, such as a car wheel, but it can also be the circular

path made by a handle that turns, such as a lever rotating around a fixed point.

 •Gear: This is not a simple machine but it could be thought of as a wheel with teeth

around its outer rim. Gears are used to transfer motion and force from one location to

another, change the direction of rotational motion and amplify the force applied to do a job.

•Rotary: This can be seen in the movement of car, bicycle and gear

wheels and in Ferris wheels or carousels as they go round and round

on an axis. It is the most commonly occurring type of motion in

a mechanism.

•Oscillating:This is an alternating, or swinging to and fro, type of

motion. It can be observed in car windscreen wipers, children’s

swings or in pendulums as they move backwards and forwards in an

arc.

•Linear:This is motion occurring in a straight line, in one direction.

Examples include the linear movement of a paper trimmer, a sliding

lock, or a conveyor belt.

• Reciprocating: This involves an alternate backward and forward

motion, in a straight line, as in the movement of a sewing machine

needle or the pistons of a car engine.

TYPES OF MOTION

4 basic forms of motion are used in mechanisms:

Education

levers and pulleys

website: www.knexeducation.co.uk

Key Terms and Scientific Definitions

•Pulley: A wheel with a groove in its outer rim that spins freely on an axle. A rope,

cable, or chain runs in the wheel’s groove and may be attached to a load. As the wheel

turns, the rope moves in either direction so that a pull down on one side will raise an object

on the opposite side of the wheel.

  •FixedPulley: A pulley attached to a solid surface; it does not move when the rope

is pulled, other than to turn in place. Fixed pulleys change the direction of an

applied force.

  •MovablePulleys: A pulley attached directly to the load being lifted; it moves

when the rope is pulled.

  •CombinationPulleys: A series of fixed and movable pulleys used together to gain

the advantages of both in doing the work.

  •BlockandTackle: A specific combination of fixed and movable pulleys used to lift

very heavy objects; the block is the frame holding the pulleys; the tackle is the rope

or cable.

•InclinedPlane: A flat surface with one end higher than the other. The most recognisable

form of an inclined plane is a ramp. Ramps make it easier to move from one height

to another.

 •Screw: A shaft (body) that has an inclined plane spiralling around it. The inclined plane

forms ridges (threads) around the shaft to become another simple machine: the screw. It

can be used to lift objects or fasten two things together.

 •Wedge: A device made of two inclined planes arranged back-to-back. Instead of

moving up the slope, wedges themselves move to push things apart. Wedges are

inclined planes that move pointed-end first and are used in many cutting tools such as

axes, knives and chisels.

Education

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