The purpose of this activity is to help pupils to identify forces and give them a language to describe forces. Exploring pupils' ideas – and making them explicit – is a central feature of this introductory work.
A circus of stations where forces can be identified, adapted to your own circumstances - for example:
- a cup on a table
- a mass hanging on a string
- a floating block
- a shoe on a slope
- some foam under a heavy book
- a stretched spring
- something leaning against the wall
- something on a weighing machine
Some force arrows:
- enough force arrows, cut from sturdy card, to give several per group
Be aware of the hazards of slipping and tripping. Don't use anything heavy enough to cause injury if it falls. Stretched out springs may cause injury if they fly back.
Pupils are invited to visit the circus stations in groups of three or four. They have to use their arrows to identify where there are forces acting and to explain to others in their group:
- What exerts the force?
- What kind of force is acting?
- What is the force acting on?
- Where shall we place the arrows to show the force?
Paying attention to the interactions of the pupils will allow you to monitor the thinking which is going down a
Wrong Track and to identify correct ideas to reinforce at a later stage, perhaps during a whole class discussion about each station.
You are likely to find opportunities to guide pupils on the exact positions of the force arrows and to encourage pupils to articulate the language of forces:
Teacher: Well done Martin, there is a force acting on the shoe in this direction. What is the name of this force?
Martin: err… friction, no, wait a minute… grip
Teacher: Good… now what's exerting the force?
As a spin-off from this activity you might be able to revisit each station to consider any sets of forces which seem to add to a resultant of zero. (Most stations are likely to be in equilibrium.)