Manual Knex 78630 Education Intro to Gears Teachers Guide (page 2 of 52) (English)

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Education

TEACHER’S

GUIDE

GEARS

UNDERSTANDING MECHANISMS

78630

Understanding�Mechanisms:

Gears�Teacher’s�Guide

Understanding Mechanisms

Education

gears

website: www.knexeducation.co.uk

WARNING:

CHOKING HAZARD - Small parts.

Not for children under 3 years.

96566-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.

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

Understanding Mechanisms

accompanying Lesson Notes can be used

for assessment or enrichment activities.

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

definitions is offered as a resource for

the teacher.

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

in approximately one hour but can be

extended using 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.)

 • Aselectionofcopymastersisprovided

for your classroom use. These comprise

illustrations and short definitions of some

of the concepts featured in the model

building activities.

 • 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.

Education

gears

website: www.knexeducation.co.uk

TABLE OF CONTENTS

A Quick Guide to Gears 4-13

Lessons 1- 5

Lesson 1: Getting Started 14-15

Lesson 2: The Crank Fan 16-25

Lesson 3: The Car Window 26-30

Lesson 4: The Blender 31-35

Lesson 5: The Stationary Exercise

Bicycle 36-40

Key Terms and Scientific Definitions 41-45

Copymasters 46-57

Your K’NEX Gears kit is part of a series

of 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:

Gears Kit

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

gears have been used in the design of

familiar products, this construction kit also

serves to make the connection between

the models they have built and the science

that makes them work.

 • Throughtheuseofinvestigative,

disassembling and evaluative activities

(IDEAs) and focused practical tasks (FPTs),

the kit provides opportunities for pupils,

working in pairs or small collaborative

groups, to explore how gears are used

to transfer movement and forces, and

to change the speed and the direction

of movement.

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

the Guide contains 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 selected K’NEX models 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. The models without

A�Quick�Guide�to�Gears

You may claim to know very little about

gears and gearing, but if you drive a car or

have ridden a bicycle, then you know how to

use them. When driving off from a stationary

position do you choose a low gear or a high

gear? What is likely to happen if you try

to use the highest gear in this situation?

Experience tells you that your car engine will

stall if you try to move off from a stationary

position using the highest gear.

When riding a bicycle you also know that

it is easier to ride up a hill using a low gear

because it will require less effort on your part

to turn the pedals. Using a low gear on a flat

road requires very little effort, the pedals go

round quickly, but the bicycle only moves

slowly. To move faster you choose a higher

gear. You now need to apply a little more

effort to turn the pedals, but you will not

need to turn them as many times as you

would do when in a low gear.

Drawing on these experiences you know the

following about gears:

 • Highgearsenableyoutomovequickly.

 • Lowgearsallowyoutomoveslowly,but

they also help increase pedal pushing

forces (effort) when needed.

What are gears and how do they work?

Gears are wheels with teeth around their outer

rim. In order to work, the teeth on gears must

interlock or mesh so that the teeth on one

gear can push against those on the other gear.

The type of gears used in the K’NEX Crank

Fan model are called spur gears because they

look like the rowels (spiked discs) on a horse

rider’s spurs.

Try this! Take two yellow K’NEX gear wheels

and see how the teeth interlink or mesh

together. Slowly turn one gear wheel against

the other. Note how, as one gear wheel turns,

its teeth push against those on the other

gear wheel to drive it round. What do you

notice about the direction(s) in which each

gear turns?

Spur gears lie in the same plane and turn in

opposite directions, but only when they mesh

together. Different sized spur gears turn at

different speeds and with different amounts

of force. Try it!

In the K’NEX Crank Fan model, gears provide

the mechanism by which the rotary motion of

the handle is transferred to the rotary motion

produced by the fan blades.

The gears are attached to axles (or shafts) to

allow them to turn.

Strictly speaking, the gears provide the

mechanism through which motion and forces

are transferred from one axle to another.

Education

A Quick Guide to Gears

Gears can also be connected using chain

links – as in a bicycle. Gears used with chains

are called sprockets. Sprockets do not mesh

with other gear wheels but with the links in

the chain. When moved, they turn in the same

direction. As with spur gears, different sized

sprocket gears turn at different speeds and

with different amounts of force. If they are the

same size, they turn at the same speed and

with the same force.

Crown gears are used to change the direction

of rotary motion through 90-degrees. Unlike

spur gears, the teeth on crown gears lie at

right angles to the rim of the wheel. When

they mesh with spur gears, they do so at right

angles to the plane of the crown gear wheel.

In many machines a large crown gear wheel is

often used with a smaller spur gear called

a pinion.

Another type of gear, known as a rack and

pinion, comprises a small spur gear (a pinion)

that meshes with a toothed bar (a rack) rather

than another toothed wheel. This means that

as the pinion is turned it pushes against the

teeth of the rack making it move sideways in a

straight line and produces linear motion. If the

rack is moved, then the pinion can be made to

rotate. The rack and pinion mechanism can be

used to convert rotary to linear motion and

linear to rotary motion.

An oscillating lawn sprinkler contains yet

another gear type – a worm gear. A worm

gear is a long single tooth that spirals around

a cylinder. Worm gears are usually used with

a spur gear to reduce the output speed of a

mechanism while, at the same time, changing

the direction of rotation through 90-degrees.

The mechanism can only turn if the worm gear

is the driver gear and not the other way round.

Because of this, a worm gear can be used as

an automatic locking mechanism.

Education

gears

website: www.knexeducation.co.uk

A�Quick�Guide�to�Gears

What are gears used for?

Gears are used in most machines with

moving parts, from clocks and cars to egg

whisks, lifting winches and hand drills. They

come in different sizes and forms depending

on the job they are designed to do.

• Changethedirectionofmotionthrough

90-degrees, as in an egg whisk, windmill

and waterwheel.

Gear basics

The K’NEX Crank Fan model mechanism

has the simplest gear arrangement, with two

meshed gears of equal size. Two or more

gears that interlock, or mesh, form a gear

train; if there is only one meshed gear on

each axle, the arrangement is known as a

simple gear train.

Gears can be used to:

 • Transferrotarymotionfromoneaxleto

another, as in a bicycle when motion is

transferred from the pedals to the

back wheel.

 • Transmitforcesfromoneaxletoanother,as

in a bicycle when force is transmitted from

the pedals to the back wheel.

 • Amplify,orincrease,outputturningforces,

as in changing gear to go uphill on a bicycle

or in a car.

 • Increaseordecreasespeed,asinchanging

gear on a bicycle or car.

Follower/

Driven

Gear

Driver

Consider a spur gear system. The first gear

wheel to be turned, and the one to which the

effort force is applied, is called the driver.

In the K’NEX Crank fan model, the driver is

the gear attached to the handle axle. The

driver transmits turning forces to the follower,

or driven, gear causing it to rotate in the

opposite direction.

Education

A Quick Guide to Gears

Follower/Driven Gear

Driver Gear

Input

Output

The number of turns, or the force, you apply

to the driver is the input movement or force;

what is produced by the follower is the output

movement or force.

Key facts about simple gear trains:

 • Inasimplegeartrainwithtwogears

the same size, the follower turns at the

same speed as the driver but in the

opposite direction.

 • Turningforcesandmovementsinput

through the driver and output through

the follower.

Slowing down

A small gear wheel turning a large gear wheel

slows the turning speed of the axle attached

to the large (follower) gear. This example

can be found in the K’NEX Crank Fan model

(See below and on Page 3 of the Building

Instructions booklet).

Follower/

Driven Gear

Driver Gear

Idler Gear

How can you make the driver and the follower

gears rotate in the same direction? Add an

idler gear between them. The addition of the

idler gear will create an odd number of gears

in the gear train and make the gears on either

side rotate in the same direction.

Follower /

Driven gear:

82 teeth

Driver: 14 teeth

Slowing down

Education

gears

website: www.knexeducation.co.uk

A�Quick�Guide�to�Gears

Follower / Driven:

14 teeth

Driver: 82 teeth

The small driver gear B must turn a number

of times for the larger follower gear A to

make one complete rotation or turn. This gear

arrangement produces a slow output speed.

The term used to describe this mechanism

is gearing down.

One of the important advantages of gearing

down is to increase (amplify) the output turning

force available. Try this! Ask someone to try

to stop you turning the handle of the Crank

Fan by holding onto the fan or output axle.

They will find it almost impossible to prevent

you from turning the handle. By gearing down,

the output turning forces have been increased

six times. (A 14-tooth driver gear will make

approximately 6 complete turns for every 1

turn made by an 82-tooth follower gear.)

Gearing down means you can use less effort.

On a 10-speed geared bicycle, the lowest gear

is usually selected to go up very steep slopes

because this is when the greatest force (pedal

power) will be needed. If, however, this low-

est gear is used on the flat, the pedals will go

round very quickly but the bicycle will hardly

move forward. To go faster, a high gear is

selected but high gears need more effort to

turn them and when used in a car, the engine

may stall when going up even a gentle slope…

that’s the trade off.

Key facts about going slower

 • Asmalldrivergearturningalarge

follower/driven gear slows the output

speed but increases the turning forces

available.

 • Themechanismbywhichthisisachieved

is called gearing down.

Speeding up

A large driver gear (B), turning a small follower

gear (A) will increase the turning speed of the

axle attached to the follower gear.

An easy modification to the K’NEX Crank Fan

model gives you this gear arrangement. Try it!

The fan now turns much faster than the handle

but it is slightly more difficult to turn the handle

than before. The output speed is increased but

more effort is needed than with the other gear

arrangement. Increasing the output speed is

called gearing up.

Ask someone to try to stop you turning the

handle by holding onto the fan. This time only

the lightest touch or resistance is needed for

the fan to be stopped, no matter how much

effort you put in.

Speeding up

Education

A Quick Guide to Gears

This is exactly the same situation as trying to

ride a bicycle up a hill in a high gear or trying

to start to drive your car by engaging a high

gear (4th or 5th gear, for example) - the bike

and the engine will stall.

Key facts about speeding up

 • Alargedrivergearturningasmallfollower

gear increases the output speed but

decreases the turning forces on the

output axle.

 • Themechanismbywhichthisisachieved

is called gearing up.

How many times faster?

Using the example of the K’NEX Crank

Fan with a 14-toothed follower (A) and an

82-toothed driver (B): For every 1 complete

turn made by driver B, almost 6 complete turns

will be made by follower A. In other word, the

ratio of input (driver) to output (follower) is

approximately 1:6

Check it for yourself.

This ratio is called the gear ratio and may also

be calculated from the number of teeth on

each gear. For example:

Gear Ratio =

Number of teeth on the follower (14)

Number of teeth on the driver (82)

5.85

This gear ratio indicates again that for every

one turn of the driver almost six turns are

produced by the follower gear wheel - the

output speed is approximately 6 times faster

than the input speed. This is called gearing up.

If, on the other hand, the follower is larger than

the driver we get the gear ratio of 82/14 or

approximately 6:1. This gear ratio indicates

that the output will be 6 times slower than the

input speed. This is called gearing down.

Think about how, when driving your car, you

go up through the gears to go faster and go

down through the gears to go slower.

Changing the direction of

movement through 90-degrees

Simple gear trains allow rotary motion and forc-

es to be transferred in a straight line.

This, however, is not always useful. Windmills

and waterwheel mills, for example, need to

be able to change a vertical, rotary motion

from the sails and the waterwheel into the

horizontal, rotary motion needed by the

grinding wheels to process grain. This problem

was solved by positioning the teeth on one

gear wheel so that they were at right angles

to its face instead of around the rim. This

meant that the two gear wheels could mesh

at 90-degrees to each other.

Examine the two yellow gear wheels used for

the mechanism in the K’NEX Blender model

and see how they mesh together.

Education

gears

website: www.knexeducation.co.uk

A�Quick�Guide�to�Gears

This drawing represents a crown gear wheel

used to change direction of movement through

90-degrees. This type of gear is called a crown

gear – when looked at from the side it looks

rather like a crown.

The mechanism is called a crown gear wheel

and pinion. The pinion is simply another name

for a follower gear.

Crown gears can be used in the same way as

spur gears for gearing down, as in the K’NEX

Phonograph model, and for gearing up, as in

K’NEX Eggbeater model.

A chain and sprocket system

Chain and sprocket systems use a chain to

transfer rotary motion from a driver’s axle to a

follower’s axle. We are perhaps most familiar

with the chain and sprocket system used in

bicycles. This gear arrangement can be seen

in the K’NEX Stationary Bike model.

Sprockets are toothed wheels on which

a chain runs. The drawing shown below

represents a chain and sprocket system as

used in the K’NEX Stationary Bike model.

Education

A Quick Guide to Gears

Chain and sprocket systems can be used to:

 • Transferrotarymotionandforces

 • Amplifyforces

 • Increaseordecreasespeed

They share these features with simple

gear trains.

They differ from simple gear trains, however,

in that:

 • Thedriverandfollowersprocketsrotatein

the same direction.

 • Theycanbeusedtoconvertrotary

motion into linear motion as, for example,

in a chainsaw (see the K’NEX Chainsaw

model), in conveyor belts used on

production lines, and on the lifting

mechanisms of fork lift trucks.

 • Chainandsprocketsystemsare 

adjustable. To increase or decrease the

distance between the two axles simply

lengthen or shorten the chain.

Key facts about chain and

sprocket systems:

Chain drive systems use a chain and

sprocket to transfer motion from the driver

axle to the follower axle. The same rules apply

to both simple gear trains and chain and

sprocket systems:

 • Withtwosprocketsthesamesizethe

input speed is the same as the output

speed.

 • Asmalldriversprocketmakesalarge

follower sprocket turn slowly but increases

the turning forces on the output axle.

 • Alargedriversprocketmakesasmall

follower sprocket turn faster but decreases

the turning forces on the output axle.

Recording: making drawings

It is important for children to record what

they have observed and discovered in their

investigations. The use of labelled drawings

is a valuable communication skill that needs

to be learnt.

Yet, if asked to make a drawing of a K’NEX

gear or other mechanism, the children’s first

reaction may well be, “ I can’t do that!” Others,

who accept the challenge, may spend the next

20 minutes making sure they have drawn every

tooth on every gear wheel.

Children’s drawings do not need to look

exactly like the K’NEX, or any other, machine

they are investigating. What is important,

however, is to demonstrate how the machine

works. To achieve this, children could be

encouraged to make drawings that show,

for example, the way in which the moving

parts connect to each other. Drawing also

helps to focus the children’s attention on

the working parts.

Education

gears

website: www.knexeducation.co.uk

A�Quick�Guide�to�Gears

Follower

34 teeth

Axle or shaft

Letter helps to

identify gear

being referred to

in written

descriptions

Driver

34 teeth

Where gears mesh

A,B

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?

How do they make other parts move?

 • Whatarethemovingpartscalled?

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

parts make?

The use of graphic symbols is a simple

technique that can be used to help the

children focus on interpreting the key parts

of the mechanism.

For example, the simple gear train used in the

K’NEX Crank Fan model could be represented

by the use of symbols and careful labelling,

as shown in the diagram at the bottom of

this page.

Education

A Quick Guide to Gears

Useful Internet Web Sites

www.coe.uh.edu/archive/

The University of Houston archive of lessons.

Search >Collections > Science >Lesson plans

>Simple Machines.

www.flying-pig.co.uk

A general site for simple machines. It

includes some simple animated drawings of

mechanisms in action.

www.howstuffworks.com

A library of information on different types

of machines. Useful background information

for teachers. Use the search facility to find

information.

www.mos.org/sln/Leonardo/

InventorsToolbox.html

A site that includes some helpful illustrations

of different types of gears.

www.smartown.com/sp2000/machines2000/

Simple machines made simpler. A good

introduction to simple machines made by

primary school children.

Some children, however, may want to pro-

duce more realistic drawings, such as this one

showing the arrangement of a crown gear, or

use photographs, taken with a digital camera,

to record their observations.

Education

gears

website: www.knexeducation.co.uk

Lesson�1:�Getting�Started

Time: 1 hour

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.

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:

Gears 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.

Education

Lesson 1: Getting Started

Teacher’s Notes

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.

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

things move.

• 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?

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

gears

website: www.knexeducation.co.uk

Lesson�2:�The�Crank�Fan

How to transfer rotary motion using a simple gear train

Time: 1 hour + 1.5 hours

Learning Objectives - Children should learn:

 •toinvestigateanddisassembleproductsinordertolearn

how they work

 •howtotransferrotarymotionusinggears

 •howgearsmaybeusedtoincreaseanddecreasespeed

 •tocommunicateinformationaboutproductsand

mechanisms through labelled drawings

Vocabulary

gear wheels, axle, handle, crank,

winder, gears, teeth, rim, opposite,

direction, clockwise, anticlockwise,

faster, slower, rotate, rotary, linear,

movement, motion, mechanism,

smaller, larger, input, output, driver,

follower, gear ratio, gearing up,

gearing down, friction, lubricant

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Gears kit with

Building Instructions booklet

• Dot stickers or pieces of

masking tape

• Felt-tipped pens

You will need:

• An electric fan

• A collection of devices and toys

that use gears

• A built model of the K’NEX

Crank Fan

Useful Internet Web Sites

Please refer to Page 13 of A Quick

Guide to Gears.

KEY STAGE 1

Possible Teaching and Learning Activities

Introduction

The Crank Fan model from the K’NEX Understanding

Mechanisms: Gears kit may be used to support the QCA/

DfEE scheme of work Exemplar Materials for Design and

Technology Unit 2C: Winding up by replacing the fan with

a string and lifting attachment. Using the K’NEX Crank Fan

model in this way demonstrates to children that similar

mechanisms can be used in different ways. It may also be

used to support Science Unit 2C: Forces and Movement –

‘Explain how to make familiar objects move faster or slower.’

Younger Key Stage 1 children are not expected to construct

the K’NEX Crank Fan model themselves but a pre-built

model could be made available for their investigations. In

addition, children may not be familiar with following step-

by-step instructions and interpreting 2D plans. Extra time

and support may be needed if this is the first time children

have been asked to make K’NEX models from 2D plans.

Whole Class

Demonstrate how an electric fan works. It may be useful

to have a partly dismantled electric fan on display. Use the

K’NEX Crank Fan model to show how that fan works.

The crank fan lesson is in two parts; the first part can be used

with Key Stage 1 children using a limited vocabulary while both

parts allow Key Stage 2 children to progressively investigate

how gears work using a more expansive terminology.

Teacher’s Notes

Use caution when displaying the

dismantled electric fan. Children

should not touch the parts.

Education

gears

website: www.knexeducation.co.uk

Lesson 2: The Crank Fan

* What are the functions of the moving parts?

* Will the fan turn if one of the gear wheels

is removed?

* Answers will vary, but children

should identify that one gear

wheel causes the other to turn

and this drives the fan blades.

* Look at how the teeth on the

gear wheels mesh together.

* Gear wheels, winder, handle…

* The handle, gears and fan all

move in circles.

* 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?

Working in Groups of 2-3

 • Ifacollectionofdevicesthatusegearsisavailable,

allow the children time to investigate/demonstrate these

and to talk about and discuss their observations.

Whole Class

 • Askthechildrentotalkaboutthewaysinwhich

gears are used to make the toys and devices they

have examined work. Explain that in this lesson they

wil investigate how gears work by investigating a

K’NEX model.

Working in Groups of 2-3

 • Distribute2gearsfromtheK’NEXUnderstanding 

Mechanisms: Gears kit to each group. Encourage them

to think about how they would describe a gear and to

explore how gears fit together. You may choose to

accept their operational definition for how gears work,

or formalize the terms they use in describing gears and

how they fit together. (For example, mesh.)

 • Distributepiecesoftapeordotstickersandaskthe

children to place a small piece of tape on each of

the two K’NEX gears so that they can observe the

This activity will allow you to

establish the children’s level of

understanding of gears. It may also

help establish that gears, in some

form, are used in the majority of

machines that have moving parts

- from cars to clocks, from toys to

computer printers.

Teacher’s Notes

* Answers will vary but expect

them to respond that the fan

blades turn.

Children may be encouraged to think about and discuss

what they are investigating through the use of facilitating

questions such as:

* What does the machine do?

* What happens when they turn the handle?

Gears are wheels with teeth

around their outer rims. As one

gear wheel turns, its teeth push

against the teeth on the other

gear wheel, pushing it around.

If the first gear wheel is turning

clockwise, then it will push the

second gear wheel in the opposite

direction i.e. anticlockwise.

This activity provides an opportunity

to introduce formal terms that the

Education

Lesson�2:�The�Crank�Fan

direction(s) in which the gears move. The children

should lay the gears on a piece of paper on their desk

so that they mesh. Suggest that one child insert a

pencil point into the central hole of each gear to hold

them in place, while the other child turns ONE gear.

 • Askthemtonoticewhathappens.

   •Dobothgearsmove?

   •Dobothgearsmoveinthesamedirection?

 •Encouragethemtoaddarrowstothegearstoshow

the direction of movement.

Whole Class

 •UsingaK’NEXCrankfanmodelcontinuetointroduce/

reinforce the new technical vocabulary and terminology

the children will use as they undertake their

investigation. For example, gear wheels, axle, handle,

winder and rotary movement.

Working in Groups of 2-3

Before the children build their K’NEX models and explore

real mechanisms, explain that they may find it helpful to

use a process, such as the one outlined here, for their

investigations. This might involve:

 •Identifyingthepartsofthemodelfrom2Ddrawings

 •Namingtheparts

 •Statingtheirfunctionsinthemodel

 •Identifyingthemovementsthepartswillmake

 •Buildingthemodel

 •Investigating

 •Determiningwhetherornottheirinitialideaswereright

Interpreting 2D drawings to

construct 3D models is an

important skill for children to learn.

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

and allow them time to investigate how their model

works. Ask them if they know why it is called a

crank fan.

The handle, or crank, behaves as

if it is a rotating lever mechanism.

The axle is the fulcrum and the

arm or crank is the lever. As when

using a lever, a longer crank is

Undertaking this type of process

will help the children’s skill

development.

children should use during their

investigations with gears.

Teacher’s Notes

You may find it useful to create

a word wall showing the range of

words and terminology the children

may need when (a) discussing

their investigations and findings,

(b) making labelled drawings and

could be written on cards, possi-

bly with simple descriptors on the

reverse side.

See A Quick Guide to Gears and

Key Terms and Scientific Definitions

for additional information.

Education

Lesson 2: The Crank Fan

 • Otherfacilitatingquestionstoaskthechildren

might include:

* What are the names of the parts that make the

fan/lifting device turn/rotate?

* What is the mechanism, used to turn the fan/

lifting device, called?

* How would they make the fan/lifting device

turn faster/slower?

* Describe the type of movement made by the

fan/lifting device?

* What is the direction of movement made by the

handle and fan?

* Do the two gear wheels turn in the

same direction?

easier to turn than a short one –

it needs less effort force. Attempting

to turn the axle itself will require a

large effort force. You can test this

for yourself by turning the crank fan

model with and without the handle.

Teacher’s Notes

* Possible answer: Gear

wheels, axles, handle.

* Possible answer: Winder,

handle, crank.

* Possible answer: Turn the

handle faster/more slowly.

* Possible answer: Rotary/

linear motion.

* Possible answer:

Clockwise/anticlockwise.

* Possible answer: In different

directions: clockwise/

anticlockwise.

* Possible answer: No.

* Will the mechanism be easier to turn without

the handle?

 • Askthechildrentoprepareandsticklabelson

their model to identify the key moving parts of the

mechanism. They should add arrows to show directions

of movement. This may help them later when they

describe their observations and findings.

Extension Activity 1

Using the fan model, you may wish to ask the children

to observe that the blades of the fan make one complete

turn or rotation for every complete turn of the handle. This

happens because the gear wheels are the same size. They

can check this by marking both gear wheels with dot stickers

at the point where the two gear wheels mesh and see what

gears

website: www.knexeducation.co.uk

Education

Lesson�2:�The�Crank�Fan

Teacher’s Notes

The following series of investigations

require the children to rebuild their

models using different sized gears.

Guidelines are provided on the right

hand side of Page 3 of the Building

Instructions booklet. We suggest

that two groups work together,

with one group building the model

with the large gear as the driver,

while the second group uses a

small gear as the driver. Having

both models available will make

comparisons easier.

happens when they turn the handle slowly through one

complete turn. The stickers will rotate in opposite directions

and will come together again in time with the handle and fan.

Whole Class

 •Talkaboutthechildren’sobservations.Encourage

them to use their K’NEX models to demonstrate

their explanations through the use of correct

technical vocabulary.

Extension Activity 2

Working in groups of 4-6 (using 2 building kits)

 •AskonehalfofthegrouptousetheirK’NEXkitto 

rebuild the crank fan so that a large gear drives a small

gear; ask the other half of the group to rebuild their

crank fan so that a small gear drives a large one.

 •Askthegroupstoinvestigatewhathappenstothe

fan/lifting device when:

* the large gear drives the smaller gear wheel?

* the smaller gear drives the larger gear wheel?

* The smaller gear wheel turns

faster.

* The larger gear wheel turns

more slowly.

* The fan/lifting device will

not work when the handle

is turned.

* the gear wheels do not mesh together?

 •Beforetheybegineachinvestigationaskthechildren

to speculate what they think will happen; then they

should try it out. Were they correct?

KEY STAGE 2

Possible Teaching and Learning Activities

Introduction

Children at Key Stage 2 are expected to develop their

knowledge and understanding as to how mechanisms

can be used to make things move in different ways.

Investigations and vocabulary can be developed in greater

depth, building on the activities from Key Stage 1. If this

is the first time children are using the kit, start with the

Key Stage 1 activities.

Education

Lesson 2: The Crank Fan

These activities will allow you to

establish/review the children’s

understanding of the use of gears.

They may also help establish that

gears, in some form, are used in

the majority of machines that have

moving parts - from cars to clocks,

from toys to computer printers.

Whole Class

Demonstrate how an electric fan works. It may be useful

to have a partly dismantled electric fan on display. Use the

K’NEX Crank Fan model to show how that fan works.

Children could be encouraged to think about and discuss

what they are investigating through the use of facilitating

questions, such as:

 •Whatdoesthemachinedo?

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

 •Howarethemovingpartsconnected?

 •Howdotheymakeotherpartsmove?

 •Whatarethemovingpartscalled?

 •Whattypesofmovementsdothemovingpartsmake?

Working in Groups of 2-3:

If a collection of devices that use gears is available, allow

the children time to investigate these and to talk about and

discuss their observations.

Ask the children to describe familiar machines that use

gears. On the board, make a list of these machines and

what they do.

Whole Class

Using a K’NEX Crank fan model introduce the technical

vocabulary and terminology the children will need. For

example: gears, input and output, mechanism, driver,

follower and gear train.

You may find it useful to create

a word wall showing the range of

words and terminology the children

may need when (a) discussing

their investigations and findings,

(b) making labelled drawings and

could be written on cards, possi-

bly with simple descriptors on the

reverse side.

See A Quick Guide to Gears

and Key Terms and Scientific

Definitions for additional

information.

Using a K’NEX Crank Fan model as an example,

demonstrate on the board how to make simple labelled

drawings, using arrows to show the direction of movement.

The diagram on Page 22, for example, is a symbolic

representation of gears in a simple gear train.

It is not necessary to draw every

K’NEX building component used

in the model – simply the key ones

used in the mechanism. Explain 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. Help to

Teacher’s Notes

Use caution when displaying the

dismantled electric fan. Children

should not touch the parts.

gears

website: www.knexeducation.co.uk

Education

Lesson�2:�The�Crank�Fan

Working in Groups of 2-3

 •AskeachpairtobuildtheK’NEXCrankFanmodeland

provide time for them to investigate how it works? You

may want to use the following to guide their inquiry:

  •Identifythepartsthatmoveandhowtheyare

connected to each other.

  •Howmanydifferentmovingpartsdoesthe

model have?

  •Whattypesofmovementareusedandproduced?

  •Identifytheinputandoutputmovementandthetype

of movement made by each.

  •Howcanthespeedoftheoutputmovement

be controlled?

 •Askthechildrentoprepareandsticklabelson

their model to identify the key moving parts of the

mechanism. They should also add arrows to show

directions of movement. This may help them later

when they describe their observations and findings.

 •Askthechildrenwhattheythinkmighthappentothe

speed of the fan if, instead of two equal sized gear

wheels, their model had:

(a) a large gear driving a smaller gear wheel.

(b) a smaller gear driving a larger gear wheel.

 •Invitethechildrentoinvestigateandseeiftheir

suggestions were correct.

Follower

34 teeth

Axle or shaft

Letter helps to

identify gear

being referred to

in written

descriptions

Driver

34 teeth

Where gears mesh

A,B

Teacher’s Notes

When introducing the extended

investigation the class should be

develop the children’s observation-

al skills by focusing their attention

on the way in which the machine

works. Ask, for example, how the

moving parts connect to each

other. Their drawings should

reflect these connections.

Some children may want to

draw the teeth on each gear

wheel as they may feel that this

is a more accurate representation

of the mechanism they have been

investigating. Older children may

count the number of teeth on each

gear wheel to indicate the different

sizes. Either method is acceptable.

Fan turns slower than the handle.

Fan turns faster than the handle.

Education

Lesson 2: The Crank Fan

Teacher’s Notes

Chain and sprocket mechanisms

(see K’NEX Stationary Bike and

Chainsaw: Lessons 7 and 8), and

belt drive mechanisms can also be

used to produce similar outcomes.

Ask those children who have bicycles with gears what they

do when they want to go faster. They change into a higher

gear: the chain connects the large “gear wheel” attached

to the pedals to the smallest gear on the back wheel. It is

harder to push the pedals in this situation but you do not

have to push them round so frequently and you move

forward faster on your bike. To go more slowly, or to ride

up slopes, a low gear is selected i.e. the largest gear wheel

on the back wheel is selected. It is easier to push, but the

pedals go round more times than they would do if using the

higher gear to travel at the same speed. Their bicycles are

examples of the use of a chain and sprocket mechanism.

It may be helpful to have a bicycle

with gears in the classroom for

demonstration purposes. You

may wish to introduce additional

technical vocabulary at this point;

this vocabulary may make it easier

for the children to describe what

is happening.

In a simple gear train mechanism

comprising two gears, the driver

gear is the one that drives the

mechanism. The driver gear is

where the input force/movement

is applied. All the other gears that

are turned or driven by the action

of this gear are called driven

or follower gears. The force/

movement produced by the last

driven or follower gear is the

output of the mechanism.

Ask the children to record their observations and results.

They should use labelled drawings and written notes, and

should apply the correct vocabulary and terminology to show

what happens in the following situations:

* The driver and follower gear wheels are the

same size.

Whole Class

Discuss the effect of changing the size of the driver and

follower gear wheels.

What other mechanisms can produce the same effect?

referred back to the K’NEX Crank

Fan Building Instructions, (see the

diagrams on the right hand side of

Page 3), to show them how to

modify their models. If time is a

concern, half the class could build

one version and the other half the

alternative version. The models could

be exchanged when observations

are completed.

* Both driver and follower

gears turn at the same

speed but in opposite

directions.

gears

website: www.knexeducation.co.uk

Education

Lesson�2:�The�Crank�Fan

See A Quick Guide to Gears for

additional information.

Gear Ratio =

Number of teeth on the follower (14)

Number of teeth on the driver (84)

e.g. 14 / 84 gives a gear ratio of 1:6

NOTE: The K’NEX Crank Fan model

uses an 82-toothed gear and a

14-toothed gear.

Teacher’s Notes

If available, a digital camera

could be used to record children’s

models and be included with

other ICT applications when

creating reports.

* The smaller follower

gear wheel turns faster

than the driver.

* The driver is larger than the follower.

* The larger follower gear

wheel turns more slowly

than the driver.

* The driver is smaller than the follower.

 • Theyshouldusearrowstoshowthedirection

of movement.

Extension Activity 1

 • Askthechildrenhowtheymightestimatethespeedof

movement of each gear wheel.

(Strictly speaking, this is the axle speed.)

 • Whatwouldthechildrenmeasuretoestimatebyhow

much the input and output speeds differ?

 • Helpthechildrentounderstandthatthesimplestway

is to mark each gear wheel, then count and compare

the number of input and output turns. For example:

Counting how many output turns are produced for

one input turn will give a simple ‘gear ratio’.

 • Amoreaccurateapproachistocomparethenumberof

teeth on each gear wheel. You can write the formula for

the gear ratio on the board:

For an 84-toothed driver turning a 14-toothed

follower gear…

To answer the question on speed

you may wish to introduce the idea

of gear ratios at this point.

 • Helpthechildrentounderstandhowthisworksout:

The circumference of the driver gear (measured by the

number of teeth) is 6 times greater than that of the

follower.

Therefore:

84 x 1 (turn of driver) = 14 x 6 (turns of the follower)

or 1:6

Education

Lesson 2: The Crank Fan

Extension Activity 2

Science: Unit 4E Friction

When the handle is turned and released the fan quickly stops

rotating. If one gear wheel is removed and the fan spun, it

will keep turning freely for a longer time.

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

 •Howmightfrictionbereducedinmachines?

 •Whatisusedinbicyclesandincarenginesto

reduce friction?

Note: Oil cannot be used with plastic construction kits but

liquid soap can act as a good lubricant and can be easily

washed off later.

Plenary Session

Ask the children to describe and explain the movements and

the function of the mechanism they have investigated.

Teacher’s Notes

You may want the children to think

about when they have travelled in a

car. The driver goes up through the

gears to go faster (1,2,3,4,5) and

goes down through the gears, to go

slower (5,4,3,2,1).

 • Thegearratio1:6indicatesthatforeveryoneturnof

the driver gear, six turns are produced by the follower

gear wheel. Or, said another way, the output speed is

six times faster than the input speed. This is called

gearing up.

 • Ontheotherhand,ifa14-tootheddriverturnsan84-

toothed follower gear we obtain a gear ratio of 84/14

or 6:1.

 • Thisgearratioindicatesthattheoutputwillbe6

times slower than the input speed. This is called

gearing down.

gears

website: www.knexeducation.co.uk

Education

Time: 1 hour

Learning Objectives - Children should learn:

 •toinvestigateanddisassembleproductsinordertolearnhow

they work

 •howtoconvertrotarymotionintolinearmotion

 •tocommunicateinformationaboutproductsandmechanisms

through labelled drawings

Vocabulary

gear wheels, axle, handle,

winder, gears, opposite, direction,

clockwise, anticlockwise, faster,

slower, rotate, rotary, linear,

movement, motion, mechanism,

input, output, driver, follower, gear

ratio, gear train.

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Gears Kit with

Building Instructions booklet

• Dot stickers or pieces of

masking tape

• Felt-tipped pens

You will need:

• A collection of devices and toys

that use gears

Useful Internet Web Sites:

Please refer to Page 13 of A Quick

Guide to Gears.

Possible Teaching and Learning Activities

Whole Class

Introduction

Children are familiar with the action of opening and closing

car windows - they turn a handle or press a button and the

window goes up or down.

 •Buthowdoesthewindowactuallygoupanddown?

 •Whathappensinsidethedoor?

This lesson is about finding out how the mechanism

operates.

Ask the children to look at the photograph on Page 4 of

the K’NEX Introduction to Simple Machines: Gears Building

Instructions booklet. Discuss the actions taking place in

the opening of the car window. The children cannot see

the mechanism in the photograph but encourage them to

describe how they think it might work. You may find the

following types of questions helpful.

* What types of movement are involved in

this mechanism?

Lesson�3:�The�Car�Window

How to convert rotary motion into linear motion

Teacher’s Notes

* (i) Rotary motion when

turning the handle/using the

electric motor and (ii) linear

motion by the window

moving up or down.

* The input movement is

rotary motion by the handle

and the output is linear

motion by the window.

* By turning the handle

clockwise or anticlockwise;

turning the handle fast or

slow; reversing the switch.

* Can you identify the input and output

movements.

* How are the movements of the window

controlled?

Education

Lesson 3: The Car Window

Teacher’s Notes

Interpreting 2D drawings to

construct 3D models is an

important skill for children to

learn.

Possible Teaching and Learning Activities

Ask the children to talk about other examples of lifting and

lowering mechanisms with which they may be familiar or

which they have investigated in previous lessons. These

may include: QCA DfEE Exemplar Scheme of Work for

Design & Technology Units: 1A Moving Pictures; 2C

Winding Up; 4B Story Books; 5C Moving Toys.

Would any of the mechanisms they have identified work in a

car window mechanism? Ask them to explain the reasons for

their suggestions.

Working in Groups of 2-3

Before the children build their K’NEX models and explore

real mechanisms, explain that they may find it helpful to

use a process, such as the one outlined here, for their

investigations. This might involve:

 • Identifyingthepartsofthemodelfrom2Ddrawings

 • Namingtheparts

 • Statingtheirfunctionsinthemodel

 • Identifyingthemovementsthepartswillmake

 • Buildingthemodel

 • Investigating

 • Determiningwhetherornottheirinitialideaswereright

 •ProvidetimeforthechildrentomaketheirK’NEXCar

Window (Pages 4-5, Building Instructions booklet) and

to investigate how it works.

Building Tips:

1. In Step 3 ask the children to pay

careful attention to the placement

of the blue Rod (with a free end)

within the white Connector.

2. Joining Step 4 to the section

built in Steps 1-3 may require more

than one pair of hands.

You may want to write these

questions/directions on the

board. This will help focus the

subsequent discussion concerning

the children’s findings.

 •Askeachgrouptoinvestigate:

* The parts that move and how they are connected.

* Gear wheels that

mesh together.

* Rotary and linear.

Undertaking this type of

process will help the children’s

skill development.

* Identify and name the input and output

movements.

gears

website: www.knexeducation.co.uk

Education

Lesson�3:�The�Car�Window

Whole Class

 •UseaK’NEXCarWindowmodeltodemonstratehow

the model works/review the children’s observations.

This will provide an opportunity for you to reinforce

existing terms and to introduce additional technical

vocabulary and terminology.

 •Askthechildrentoprepareandsticklabelson

their models to identify the key moving parts of the

mechanism and the directions of movement. This

activity may be of help later when they describe their

observations and findings.

Teacher’s Notes

* To slow the movement of the

window and to increase the

output force.

* Turn the handle faster.

* Why a small gear wheel is used as the driver to

turn a large follower.

* How they can control the speed of the output

movement.

* Why the handle turns many times but the window

only rises very slowly.

* The mechanism is gearing

down: the handle is attached

to a small gear wheel that

turns a large gear wheel.

* Not easier – the long handle

works in a similar way to

a lever.

* A crank.

* Whether or not the mechanism will be easier to

turn without the handle.

See: A Quick Guide to Gears

and Teacher’s Notes for Lesson

2: Crank Fan for additional

information.

As part of the demonstration and

discussion you may find it useful

to add any new terms that arise

to the class word wall. These will

help the children as they create

labels, discuss their investigations,

make labelled drawings and write

descriptions.

Words could also be written

on cards, possibly with simple

descriptors on the reverse side.

The window is operated by a

simple crank system (the handle),

which turns the first of two simple

gear trains inside the door.

These gearing mechanisms are

designed to slow up the final

output movement of the window.

 •Asareview,youcouldaskforvolunteerstotaketurns

to describe, step-by-step, what occurs from the point

where effort is applied to the handle, to the point

where the window is raised. Use the following to start

the explanation:

“Turning the crank handle anticlockwise causes the tan

gear wheel to…”

* Ask the children to provide the technical name

(other than handle) for the mechanism used to

open and close the window.

Education

Lesson 3: The Car Window

This slowing is called gearing

down. In the first gear train, a small

(tan) driver gear (14-teeth) drives

a larger (yellow) follower gear (34-

teeth), while in the second gear

train another 14-tooth gear drives a

large 82-toothed gear. This twofold

slowing down process causes the

large 82-toothed gear to move

very slowly. A consequence of

this slowing or gearing down is to

increase the turning forces available

to lift the heavy glass window.

As a possible extension activ-

ity you might ask the children

to observe how many times the

14-toothed tan driver gear wheel

must be turned to make the

34-toothed yellow follower gear

wheel turn once – approximately

two and a half turns. This number

gives an approximate measure of

the gear ratio of this part of the

mechanism. In this case the gear

ratio is 2.5:1, which indicates that

the input speed is two and a half

times faster than the output speed.

Put another way, the output speed

is two and a half times slower than

the input speed.

In the second gear train, the small

tan driver gear would have to turn

approximately 6 times to turn the

very large yellow follower gear

once. In this case the gear ratio will

be 6:1. The window opening mech-

anism, however, will not

allow one complete turn of the

large yellow follower gear wheel

to be made.

See: A Quick Guide to Gears and

Lesson 2: Crank Fan for additional

information.

 • Askthechildrentoinvestigatehowthewindowis 

moved by the second gear train.

 • Howisthemotionofthewindowdifferentfromthe

motion of the handle/winder and the gears?

Teacher’s Notes

The window is raised using a

lever arm connected to the axle of

the largest yellow gear wheel. As

the yellow gear wheel turns, the

Follower /

Driven gear:

34 teeth

Driver: 14 teeth

Follower /

Driven gear:

82 teeth

Driver: 14 teeth

Gear Train 1

Gear Train 2

gears

website: www.knexeducation.co.uk

Education

Lesson�3:�The�Car�Window

window arm moves up and down.

The movement of the arm raises

and lowers the window. Notice

how the vertical part of the window

raising mechanism always stays

vertical. Its motion is linear while

the handle and gears rotate.

This mechanism is an example of

a linkage. A linkage is an important

control system because it allows

forces and movements to be

transferred. It also changes the

direction of a force or makes things

move in a particular way. Calliper

brakes on bicycles, treadle sewing

machines and toolbox drawers

that stay level when opened are

examples of linkages.

Linkages based on a parallelogram

can be used to make two sides

move together or stay parallel to

each other as the linkage moves.

See diagram opposite.

 •Askthechildrentorecordtheirobservationsandresults

using labelled drawings and notes. They should make

use of the correct vocabulary and terminology to show

how the window opening mechanism works. They

should use arrows to show the direction of movement.

Extension Activity 1

 •Askthechildrentodiscusswhyitisimportantforacar

window to move slowly.

 •WouldthechildrenallowtheK’NEXmodeldesignfora

car opening mechanism to be used in a car? They

should explain their reasons.

 •Askthechildrentoconsiderhowusingthickerglass

would affect the design of the car window mechanism.

 •Manymoderncarshaveelectricwindows.What

important safety features should be included in the

design of the window opening mechanism? Think

about who might be using the car, where they might

be sitting and whether or not they are able to operate

the window controls.

Plenary Session

Ask the children to discuss and explain the movements and

the function of the mechanism they have investigated.

Teacher’s Notes

Using thicker glass means that

the window will be heavier. The

gear mechanisms may need to

be modified to produce a greater

output force.

To promote the wider use and

application of ICT skills and

practices, the children’s models

and work can be recorded using

a digital camera.

Education

Lesson 4: Blender

Time: 1 hour

Learning Objectives - Children should learn:

 •toinvestigateanddisassembleproductsinorderto

learn how they work

 •howtochangethedirectionofrotarymotionthrough

90-degrees

 •tocommunicateinformationaboutproductsand

mechanisms through labelled drawings.

Vocabulary

gear wheels, axle, handle, winder,

gears, clockwise, anticlockwise,

faster, slower, rotate, rotary, crown

gear, right angle, 90-degrees,

vertical, horizontal, spur gear,

mechanism, input, output, driver,

follower, gear ratio, gear train

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Gears Kit with

Building Instructions booklet

• Dot stickers or pieces of

masking tape

• Felt-tipped pens

You will need

• Food blender

• Ingredients for blending

Useful Internet Web Sites:

Please refer to A Quick Guide to

Gears, Page 13.

Possible Teaching and Learning Activities

Introduction

Whole Class

 • Talkabouthow,inthepreparationoffood,some

ingredients may need to be chopped up into small

pieces. Demonstrate the process using a knife and

using a blender and discuss the needs, advantages

and disadvantages of both processes.

 • Demonstratehowarealblenderworksand

talk about:

  •Thedifferentusesofblendersandhowdifferent

materials are used in the blender for different

purposes. For example: metal blades for cutting,

plastic or glass for the container and plastic for

the body of the blender (to cover the electrical

components).

Teacher’s Notes

This activity may also provide an

opportunity to talk about the aes-

thetics and functionality of the

blender design.

• What do the children like or

dislike about the design?

Shape? Colour? Noise? Can

they provide reasons for

their opinions?

• What important safety issues

must be considered in the

design of equipment that

handles food?

Lesson�4:�Blender

How to change the direction of rotary motion through 90-degrees

gears

website: www.knexeducation.co.uk

Education

• What important safety

issues are there for the user?

Electrical precautions?

Sharp cutting tools?

Precautions required if

operated by children?

Teacher’s Notes

Interpreting 2D drawings to

construct 3D models is an

important skill for children to learn.

Ask the children to build their K’NEX Blender model

(Pages 6-7, Building Instructions booklet) and provide them

with some time to investigate, record and discuss how the

mechanism works.

 •Tohelpthechildrenseethedirectionsofmovementof

each gear wheel they might place a dot sticker or piece

of masking tape on each one and an arrow to show the

direction of movement.

Undertaking this type of process

will help the children’s skill

development.

 •Howsomeblendersusedifferentspeedsettingsin

order to chop, beat or homogenize the food.

 •Explaintothechildrenhowtheywillinvestigateone

possible mechanism to operate the cutting blades of a

blender. Their blender will be hand operated.

 •Reviewwiththechildrenthewayinwhichthespur

gear system in their K’NEX Crank Fan could either

change the output speed or change the output force.

Explain that a spur gear is just one type of gear

arrangement. In the blender they will encounter a

different arrangement that carries out a different job.

Working in Groups of 2-3

Before the children build their K’NEX models and explore

real mechanisms, remind them that they may find it helpful

to use a process, such as the one outlined here, for their

investigations. This might involve:

 •Identifyingthepartsofthemodelfromthe2Ddrawings

 •Namingtheparts

 •Statingtheirfunctionsinthemodel

 •Identifyingthemovementsthepartswillmake

 •Buildingthemodel

 •Investigating

 •Determiningwhetherornottheirinitialideaswereright

You may want to write the

following questions/directions

on the board. This will also help

focus the subsequent discussion

concerning the children’s findings.

Lesson�4:�Blender

Education

Lesson 4: Blender

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

what they are doing through facilitating questions such as:

* Identify and describe the parts that move and

explain what they do.

Teacher’s Notes

* Gear wheels move. They

transfer rotary movement

and force.

* Crank: vertical; 1st gear:

vertical; 2nd gear: horizontal;

blades: vertical.

* The crown gear wheel

meshes at right angles to

another smaller spur gear;

this changes the direction

of motion so that one gear

turns vertically and the

other horizontally.

* Rotary in and rotary out.

* Identify the parts that move in a vertical plane

and those that move in a horizontal plane.

* How are the moving parts connected so

that they create the change in direction

of movement?

* Identify and name the input and output

movements.

* Where does the output motion take place?

* It occurs at the chopping

blades.

* The driver gear is attached

to the handle and the

follower gear moves the

cutting blades.

* Clockwise /anticlockwise.

* Identify the driver and follower gears.

* What is the direction of rotation of the driver

and follower gears?

* How is the speed of the output movement

controlled?

* Why does the handle rotate at the same speed

as the cutting blades?

* Will the mechanism be easier to turn without

the handle?

* Does this gear system change speed, force or

direction of motion?

* By turning the handle faster.

* The gear wheels are the

same size.

* No.

* It changes the direction

of motion.

gears

website: www.knexeducation.co.uk

Education

Lesson�4:�Blender

Whole Class

 •UsingaK’NEXBlendermodel,demonstrateand

introduce/reinforce the vocabulary the children should

use when describing the working of their model. For

example: input and output, mechanism, driver,

follower and crown gear wheel mechanism.

 •Explaintothechildrenthattheyhavebeenexploring

a crown gear system. This gear system is used to

change the direction of motion. Ask them to take one

of the spare gear wheels from the kit and suggest a

reason why the name “crown” is used.

Teacher’s Notes

You may need to demonstrate

how the yellow gears have “teeth”

that are set at 90-degrees to the

surface of the gear wheel.

Looked at from its side the gear

wheel looks like a crown – hence

its name: crown gear wheel.

These teeth, at right angles to

the surface of the wheel, mesh

with those on the rim of a second

gear wheel to give the 90-degree

change in direction.

The follower or driven gear is

sometimes called a pinion and the

mechanism is called a crown gear

wheel and pinion.

Other gear wheels, whose teeth

are around the rim, are called spur

gears – because they look like the

rowels on a horse rider’s spurs.

As part of the demonstration and

discussion you may find it useful

to add new terms to the class

word wall to help the children

when they create labels, when

discussing their investigations and

when making labelled drawings

and writing descriptions.

Words could be written on cards,

possibly with simple descriptors on

the reverse side.

Using the K’NEX Blender model as an example, demonstrate

on the board how to make simple labelled drawings, using

arrows to show the direction of movement. For example:

Spur gear

turning

cutting

blades

Crown gear

Handle

See: A Quick Guide to Gears

for additional information.

Education

Lesson 4: Blender

Working in Groups of 2-3

Ask the children to record their observations and results

using labelled drawings and notes. They should employ

the correct vocabulary and terminology to show how the

mechanism works. Their drawings should have arrows to

show the direction of movement.

Whole Class

Talk about how the model is constructed and how the

components are joined together to create a stable structure.

 • Whyisitimportantfortheblendertohavea

stable structure?

 • Howisthisachievedinthereallifeexample?

 • Whereisheaviestpartoftheblendertobefound?

Extension Activity

Talk about other familiar mechanisms that can produce a

similar change in direction and the types of machines that

make use of them. For example:

 • Eggwhiskshavealargecentralgearwheelthatisused

to produce two outputs. The whisks have to turn very

fast to make an effective whisking action. Hand drills

often use bevel gears, while adjustable spanners use

worm gears. Bevel gears have their rims bevelled to an

angle of 45-degrees so that when the gear teeth mesh

they form a 90-degree angle. Hand drills have a slow

output movement to enable the cutting action of the drill

to be controlled. Compare this type of movement with

that of the egg whisk mechanism.

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.

Building instructions for a K’NEX

model of an egg whisk are

provided on Pages 10-11 of the

Building Instructions booklet.

You may want to use this model

as an enrichment activity.

 •Pulleywheelsalsochangethedirectionofmovement–

a pull down results in a pull up.

 •Roundbeltstwistedthrough90-degreesareusedin

some vacuum cleaners where the motor and brushes

are at 90-degrees to each other.

Plenary Session

Ask the children to explain the movements and the function

of the mechanism they have investigated.

gears

website: www.knexeducation.co.uk

Education

Time: 1 - 1.5 hours

Learning Objectives - Children should learn:

 •toinvestigateanddisassembleproductsinorderto

learn how they work

 •howtotransfermotionandforcesusingachainand

sprocket mechanism

 •tocommunicateinformationaboutproductsand

mechanisms through labelled drawings

Vocabulary

axle, handle, crank, gears, sprocket,

chain, chain drive, rim, opposite,

clockwise, anticlockwise, faster,

slower, rotary, movement, motion,

mechanism, input, output, driver,

follower, gear ratio, gearing up,

gearing down, speed, modify

Resources

Each group of 2-3 children

will need:

• 1 K’NEX Understanding

Mechanisms: Gears Kit with

Building Instructions booklet

• Dot stickers or pieces of

masking tape

• Felt-tipped pens

You will need

• Stationary exercise bicycle (or the

K’NEX model) and/or a bicycle

Useful Internet Web Sites:

Please refer to A Quick Guide to

Gears, Page 13.

Possible Teaching and Learning Activities

Introduction

Whole Class

 •Reviewwiththechildrenthewaysinwhichgearsare

connected and how motion and forces are transmitted

through a gear system.

 •Talkaboutthedifferencestheyhaveidentifiedbetween

spur gears and crown gears. The spur gear system

changed the output speed or amplified the output

force. The crown gear system changed the direction

of motion through 90-degrees. In both cases, however,

the gears meshed or touched each other.

 •Explainthatinthislessontheywillexploreanother

type of gear system, one in which the gears do not

touch each other. This gear arrangement is the system

that is used in bicycles. Explain that they will examine

how it operates in a stationary exercise bicycle.

 •Talkabouthowpeopleneedtoexercisetokeepfit

and healthy.

  •Whatsortofactivitiesdothechildrentakepartinto

keep themselves fit?

 •Manypeopleusefitnessclubswithspecially

designed machines.

  •Askthechildrentoidentifydifferenttypesof

exercise machines.

  •Whatpartsofthebodyaretheexercisemachines

designed to exercise?

  •Howdotheymeetthisneed?

 •Cyclingisahealthyandverypopularactivity,butuntil

the development of the stationary exercise bicycle it

was not possible to do it indoors.

 •Discusshowthestationaryexercisebikedesignis

based on a 2-wheeled bicycle.

Lesson�5:�The�Stationary�Exercise�Bicycle

How to transfer motion and forces using a chain and sprocket mechanism

Education

Lesson 5: The Stationary Exercise Bicycle

Foot power, via the pedals

 •Ifpossible,provideanexampleofanexercisebike

(you could use the K’NEX model) or a bicycle for the

children to investigate. Alternatively, ask the children

to look at the photograph on Page 12 of the Building

Instructions booklet to interpret how they think the

mechanism works.

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

discuss what they are doing through facilitating

questions such as:

  •Whatdoesthemachinedo?

  •Howwelldoesitdothejobitisdesignedtodo?

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

  •Howarethemovingpartsconnected?Howdothey

make other parts move?

  •Whatarethemovingpartscalled?

  •Whatstopsthebikefromfallingover?

  •Wheredoesthepowercomefromtodrive

the bicycle?

  •Howisthepowertransferredtothedrivewheel?

  •Whenridingabicycle,inwhichgearisithardest

to push the pedals round?

 •Astheydescribeitsworkings,encouragethechildren

to use terms they already know that are associated with

a bicycle’s gear system.

Working in Groups of 2-3

 • AskeachgrouptobuildandinvestigatetheirK’NEX

Stationary Bike model (Pages 12-13 of the Building

Instructions booklet) and provide time for them to

investigate their model.

Whole Class

 • Usingastationarybikemodel/bicycle,demonstrate

and explain the input and output movements, pedal,

sprocket, chain drive mechanism, links, driver,

follower/driven gear, and axle.

By a chain and sprocket mechanism.

The highest gear.

Teacher’s Notes

Write the questions you want

the children to investigate on the

board for reference and post

activity discussions.

As part of the demonstration and

discussion you may find it useful

to add new terms to the class

word wall to help the children as

they create labels, discuss their

investigations, make labelled

drawings and write descriptions.

Words could be written on cards,

possibly with simple descriptors on

the reverse side.

gears

website: www.knexeducation.co.uk

Education

Lesson�5:�The�Stationary�Exercise�Bicycle

 • Withthemodelasanexample,demonstrateonthe

board how to make simple labelled drawings, using

arrows to show the direction of movement. The diagram

below, for example, could be used as a symbolic

representation of a chain and sprocket drive system.

The chain and sprocket drive

system uses a chain to transmit

rotary motion from a driver axle to

a follower or driven axle. Sprockets

are toothed wheels on which a

chain runs. The sprockets are

placed a certain distance apart

and the chain links mesh with

the teeth on the sprocket so that

turning the driver sprocket moves

the chain and thus turns the

driven or follower sprocket.

Spur gears must mesh to transmit

movement but with a chain drive

mechanism the distance between

sprockets can be adjusted by

shortening or lengthening the

chain.

See A Quick Guide to Gears for

additional information.

 • Encouragethechildrentorecordtheirobservations

through the use of labelled drawings and notes. They

should employ the correct vocabulary and terminology

to show how the chain and sprocket drive mechanism

works. They should use arrows to show the direction

of movement and indicate the speeds of movement of

each sprocket.

 •Childrenshould:

  •Describethepartsthatmoveandtheirfunction.

  •Showhowthegearsareconnectedtotransferthe

drive force from the pedals to the rear wheel.

  •Identifyandnametheinputandoutputmovements.

  •Identifythedirectionofrotationofthepedalsandrear

wheels. Use the terms clockwise/anticlockwise.

 •Askthechildrentorespondtothefollowingquestions

using the word, “because…”

* Do the pedals rotate at the same speed as the

rear wheel?

* Do the pedals and rear wheel turn in the

same direction?

To help the children see the

directions of movement of each

moving part they might place a

dot sticker or piece of masking

tape on each sprocket and one

on the chain.

The teeth on the sprockets mesh

with the chain links and push it

along when they turn. The chain

connects the two sprockets.

* Yes, because the sprockets

are the same size.

* Yes.

Education

Lesson 5: The Stationary Exercise Bicycle

* Will the mechanism be easier or more difficult

to turn without the pedals?

* More difficult because a

pedal functions just like a

crank handle in a winding

mechanism. It helps to

amplify turning forces.

Whole Class

 •Discusshowthepedalsonabicyclearesimilartothe

handle (crank) in a winding mechanism and in the other

K’NEX models they have made, such as the crank fan,

blender and record player.

  •Wouldlongerpedalcranksbeeasiertoturn?

  •Woulditbeagoodideatohavelongerpedalsona

bicycle? If not…why not?

 • Talkaboutthedifferencesandsimilaritiesbetween

sprocket and chain drive mechanisms and simple

gear trains.

 • Askthechildreniftheycanthinkofonereasonwhy

a bicycle uses a chain and sprocket system and not a

spur gear system.

You may find it useful to have a

K’NEX Crank Fan model available to

compare with the children’s K’NEX

Stationary Bike models. Both models

use the same sized driver and

follower gears. In both cases the

number of input turns by the pedal

crank will equal the number of

output turns produced by the wheel.

In other words the gear ratio in both

drive systems is 1 to1.

The main differences are:

(a) The direction of rotation. In

the stationary bike’s chain and

sprocket mechanism, both driver

and follower rotate in the same

direction, whereas in the K’NEX

crank fan model – a simple gear

train using spur gears – the gears

rotate in opposite directions. If a

spur gear system were used on

a bicycle you would need to

pedal backward in order to

move forward.

(b) In the chain and sprocket

mechanism the rotary motion is

transmitted over a longer distance,

determined by the length of

the chain, whereas spur gears

must mesh.

Teacher’s Notes

Bicycle pedals are another example

of a crank, identical in practice to

the handle operating the K’NEX

Crank Fan model. Cranks work as if

they are rotating levers. Remember

that long levers allow you to create

large turning forces.

gears

website: www.knexeducation.co.uk

Education

Lesson�5:�The�Stationary�Exercise�Bicycle

 • Askforvolunteers,takingturns,tosummarizethe

way in which motion is transferred through the station

ary bike system. The first volunteer should start the

description at the pedals and the last volunteer

describes what happens at the rear wheel.

Teacher’s Notes

Turning the pedals transfers

motion and energy through the

driver axle to the sprocket at the

front of the bike (driver sprocket).

As the front sprocket turns, motion

is transferred to the chain. The

chain transfers motion and energy

to the rear sprocket (follower

sprocket). The turning of the

follower sprocket turns the

rear wheel.

 • Discusshowtheymightmodifytheirstationarybike’s

drive mechanism to make it harder to push the pedals.

This would make the person exercising on the bike work

harder. They should be prepared to explain the reasons

for their proposed modifications.

 • Referthechildrento:

  • ThephotographonPage12.Dothesizesofthe

wheel casings give them a clue?

  • TheoutcomesoftheirinvestigationsusingtheK’NEX

Crank Fan model.

(i) One possible way is to make

the driver sprocket larger. This will

cause the back wheel to turn much

faster but it will need more effort to

turn the pedals – just like using a

high gear on a bicycle.

(ii) A second way might be to make

the pedal cranks shorter. Because

a crank acts like a rotating lever,

a short lever will not be able to

amplify forces as much as a long

lever. More effort, therefore, will

be needed to turn the pedals.

There are not enough K’NEX

components in one kit to do this

activity. Two groups of children

will have to work together.

At the end of the lesson ensure

that the parts are returned to the

kits from which they were taken

and that the children check the

contents of each kit.

Extension Activity 1

If time is available, ask the children to modify their bike

models to meet the new specification.

Plenary Session

Ask the children to explain the movements and the function

of the mechanism they have investigated.

What would they do to improve the stationary exercise

bike design?

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

gears

website: www.knexeducation.co.uk

Education

Key�Technical�Terms��

and�Scientific�Definitions

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.

Education

Key Terms and Scientific Definitions

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

gears

website: www.knexeducation.co.uk

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

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

gears

website: www.knexeducation.co.uk

Gears: Changing direction,

speed, and force...

A gear is a wheel with teeth along its outer rim.

Gears can:

•ChangetheDIRECTIONinwhichsomethingmoves.

•ChangetheSPEEDatwhichsomethingmoves.

•ChangetheFORCEneededtomakesomethingmove.

COPYMASTERS

Gears: On the move

DRIVER GEAR:

The gear to which the effort force is applied.

FOLLOWER/DRIVEN GEAR:

The gear connected (meshed) to the driver gear.

Follower/Driven

Gear

Driver Gear

COPYMASTERS

GEAR TRAINS: Changing

the direction of rotation…

Two or more gears meshed together make up a gear train.

Meshed gears turn in opposite directions.

An idler gear makes the gears on either side of it turn in

the same direction.

Follower/

DrivenGear

Driver Gear

Idler Gear

COPYMASTERS

CROWN GEARS:

Changing planes…

A crown gear meshes at right angles (90-degrees) to another

gear and changes the direction of motion. One gear turns

vertically (up and down), while the other turns horizontally

(side to side).

COPYMASTERS

GEAR TRAINS: Changing

speed and force

SPEEDING UP/GEARING UP:

A large driver gear makes a small follower gear turn faster.

This increases turning speed, but reduces turning force.

Large driver

gear - (slow)

input

Small follower gear

- (fast) output

Small driver

gear - (fast)

input

Large follower gear

- (slow) output

SPEEDING DOWN/GEARING DOWN:

A small driver gear makes a large follower gear turn

more slowly. This reduces turning speed, but increases

turning force.

COPYMASTERS

GEARS: Try This ...

Which way will these gears turn?

c) f)

a) d)

b) e)

COPYMASTERS

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Knex 78630 Education Intro to Gears Teachers Guide Manual

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