Simple Machines – Principle Models: Levers

Things to talk about:
• What do you know about this simple machine?
• Where do we use this simple machine?
• Why do we use this simple machine?
Relate students’ answers to some of the images from “Images for Classroom Use” or find ideas from the “Overview: Levers” section to stimulate students’ interest.

Build C1 (First class lever C1).
Follow Building Instructions C, pages 4 to 12, steps 1 to 10.

Label the lever.
Draw lines from the words to the picture of the model.
First class levers have the pivot positioned between the effort and the load.

Classify an item.
Which real life item is a first class lever?
A crowbar is a first class lever.

Try out the model and make observations.
Try out lever C1. Assess and make a note about the amount of effort needed to move the load.

Build C2 (First class lever C2).
Follow Building Instructions C, page 14, step 1.

Try out the model and make observations.
Try out lever C2. Assess and make a note about the amount of effort needed to move the load. Observe how the difference in length from the pivot to the load affects the amount of effort needed to move the load.

After testing both levers, compare your observations and explain, either by writing your answer or by drawing with different sized arrows, how much effort is needed with each lever.
Lever C1 needs the least amount of effort (the smallest arrow) to move the load, because it has the shortest distance from the pivot to the load compared to lever C2.

Try other lessons!
Now that you have mastered the principles of pulleys try the Catapult lesson.