Demonstrate to students the parts of the lever and how to set it up:
The paint stirrer/ruler is the lever arm; the pencil is the fulcrum (which will form the pivot point).
Balance the lever arm on the fulcrum, so that it can tip back and forth like a see saw.
Make a ball to of foil, place it on one end of the lever, then push down on the other end of the lever to project the foil ball upwards.
After students have played for a while, ask students to start taking measurements. They should make sure they can exert the same force on the lever each time to project the ball to consistent heights. Then, while using this consistent force they can measure the height the ball is projected for different positions of the fulcrum.
Students can be taught standard notation to record their results: the lever is drawn as a straight line and the fulcrum is a triangle under the line in the correct position. Students should add arrows showing where they apply force (“force in” or “effort”), and where the resulting force is felt to project the ball (“force out” or “resistance”). They should add notes or parts to their drawing to indicate the height the ball is projected. Older students might want to use metre sticks to measure how high the ball goes, and record results.
This activity can be used to conclude that:
1. A lever changes the direction of a force (your hand pushes down, the foil ball goes up)
2. The different ends of the lever move by different amounts, depending on where the fulcrum is placed. (When one end moves further it can project the foil ball higher.)
Students may also start experimenting with balancing the lever with different sized foil balls (like a see saw). See this balancing activity for further ideas to suggest if they go this route.
Students can also use these materials and be given additional materials to try lever free experimentation, for some less structured exploration of levers, probably best done after these more structured activities.