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Activity

Lever experimentation: projecting a ball

Summary: 
Use a simple class 1 lever to project a ball of foil. Experiment with changing the position of the fulcrum.
Science content (2016 curriculum): 
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Physics: Simple and complex Machines (5)
Science topic (2005 curriculum connection): 
Physical Science: Force and Motion (grade 1)
Physical Science: Forces and Simple Machines (grade 5)
Lessons activity is in: 
Materials: 
  • ruler, paint stirrer, or other flat stiff piece of wood/plastic about 30cm long (for the lever)
  • pencil with flat sides (for the fulcrum)
  • piece of foil
Procedure: 

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.

Notes: 

Using a ruler allows students to easily read off and take note of the position of their fulcrum. Adding a gram scale to weigh lumps of play dough would allow for some great data collection comparing balance points for varying lever lengths and load weights.

The ridged pencil can make it tricky to balance the lever in the first activity - add a small piece of play dough under the pencil to hold it still - maybe in combination with a smooth, round pencil?

To measure the height projected in activity 2, do it near a wall with a ruler up the wall - one student can asses the height while another projects the foil ball.

I initially used ping pong balls intend of foil, but they bounce chaotically around the classroom and get lost easily; they also need a tiny piece of play dough to attach them onto one end of the lever.

Grades tested: 
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Teacher: 
Despina Petrellis
Ebru Montagano
Ingrid
Lindsay Izat
Teaching site: 
Bayview Elementary
Carnarvon Elementary
General Gordon Elementary Science Club
Activity originally developed and delivered: 

Gordon Elementary Science Club