A collection of levers
Classroom Activity for 11-14
What the Activity is for
Experimenting with levers.
Here pupils get their hands on devices based on levers, and get to describe and analyse them as such. You might choose to do this as a circus, where each group tries everything, or as a series of presentations, where each group of pupils prepares one example then reports back, or as a series of demonstrations (perhaps less fruitful here).
What to Prepare
A collection of levers, for example:
- a wheel brace with a mounted nut
- a large pair of kitchen scissors
helping handfor opening jam jars (with a jam jar)
- a hammer lifting a nail
- a bike brake lever, a spanner and mounted nut
- a screwdriver and mounted screw, a screwdriver and tin lid to be forced off
- an Allen key and mounted bolt, a mounted tap
- a mounted rotating door handle
(It depends what you can find easily! But do beware of compound levers, such as nail clippers…).
- each group will also need a coloured perspex rod or piece of dowel, about 15 centimetre long
What Happens During this Activity
For each device we suggest the following series of actions:
- Find out what the device is for and model the action you'd expect to carry out for it (for some classes you might need to have some prepared cards for some devices).
- Use the coloured rod to show the axis around which everything spins. This will help you to find the pivot. You might find it helpful to keep this in place while you do the rest of the analysis.
- Identify the input and output forces.
- Decide which force moves farthest as you spin the lever.
- Make a connection between these movements and the lengths to the pivots.
Keeping a record of all this thinking will be too time consuming, but you might like to choose an example for the pupils to record in some detail. It might save a lot of time if you are able to provide them with a printed copy of a carefully chosen photograph of the example, complete with the coloured rod correctly positioned. You'll have to take the picture rather carefully, so that they can annotate a photocopy of it with the forces, lever and lengths.