• Presentation: Evaluating gears.
• Equipment to make gears (per group – see Main event):
  • 1 piece of A4 double-faced corrugated card (see Teacher knowledge);
  • 1 long, thin strip of single-faced corrugated card (minimum 2 cm by 24 cm);
  • 25 paper clips;
  • 1 thumb tack;
  • 1 toothpick;
  • 1 small ball of modelling dough;
  • 1 heavy book;
  • 6 normal-length split pins to make handles for the gears (optional);
  • 1 glue stick;
  • scissors (one each);
  • access to quick-drying PVA glue (see Teacher knowledge).
• Equipment to make a gear system mounting board (per group – see Main event):
  • 1 piece of A4 double-faced corrugated card (see Teacher knowledge); 
  • 2 extra-long split pins;
  • 1 small ball of sticky tack to make handles for the gears (optional);
  • 2 small balls of modelling dough to stand the mounting board upright (optional).
• Link: Assessment – D&T: Y5: Mechanisms: Gears and pulleys (optional – see Attention grabber).

The Knowledge organiser provides a visual summary of the key facts and vocabulary for the unit. The children can use it throughout the unit to check keyword meanings or spellings and to help them remember important information when completing an activity. Find further ideas for using the Knowledge organiser to support adaptive teaching here.

Teacher knowledge

Gears

• A gear is a wheel with teeth.
• A gear system is a set of gears that fit together to change the speed, direction or force of movement.
• Larger gears with more teeth turn slower while smaller gears with fewer teeth turn faster.
• The input is where the force or motion starts and the output is where the force or motion ends after passing through the gears. For example, when pedalling a bicycle (input), the gears turn and make the wheels spin (output).
• Gears transmit power from one part of a machine to another.

Examples

• Changing gears on a bicycle to make pedalling easier.
• Clocks use gears to control the movement of the hands accurately.
• Car transmissions use gears to adjust the vehicle’s speed.
• Wind turbines use gears to increase the speed of the generator, making it easier to produce electricity from the slower turning blades.

Importance of gears

• Gears make work easier by changing the amount of force needed or the direction of movement. They help machines complete tasks more efficiently.
• These simple machines leverage the basic principles of physics to reduce the effort needed to perform tasks, making everyday activities easier and more efficient.

Cardboard

• Single-faced corrugated cardboard has one smooth side and one ridged side and can be used to create teeth on gears.
• Double-faced corrugated cardboard has two smooth sides with ridges sandwiched between them: this card is used in packaging boxes.

Misconceptions

The children may think that:

• ‘All gears turn at the same speed’ – gears of different sizes or with different numbers of teeth turn at different speeds. Larger gears with more teeth turn slower while smaller gears with fewer teeth turn faster.
• ‘Input and output are always the same’ – the input force or speed applied to a gear is not always the same as the output force or speed. Gears can change the amount of force and speed transferred, increasing or decreasing them based on their design.
• ‘A single gear can be effective’ – a single gear is ineffective because gears need to work in pairs or systems to transfer motion and force from one part of a machine to another. A lone gear cannot perform this function by itself.

Lesson organisation

• Save all gears, gear systems and mounting boards for repeated use throughout the unit.
• Reuse double-faced, corrugated cardboard from boxes and packaging to reduce costs.

Making gears

The groups need to make six gears in total. Each gear requires three layers of card and one set of teeth to be made. 

• Groups of two: any children skilled at sticking, using scissors and making could work in pairs, with each partner making one of each type of gear (three gears each).
• Groups of three: the children with some skill could work in groups of three, making one pair of gears each.
• Groups of six: less skilled children could work in groups of six, with each child focussing on making one gear.

Make pots of quick-drying PVA glue accessible to the pupils. Use paint brushes or lolly sticks to spread the glue if the pots do not have a nozzle.

Troubleshooting

• The two circles to create the gears must be stuck together with the template side facing outwards so the dot in the centre can be seen when making a hole for the axle.
• The single-faced corrugated card strips must be cut across the ridges to create teeth not along a single ridge.

Health and Safety

Remind the pupils:

• Use the equipment only as instructed by the teacher.
• Handle the scissors with care, cutting away from their fingers.
• Handle the thumb tack and split pins carefully, being careful not to touch the sharp ends.