A LEVER is a simple machine that is a bar (lever arm) resting on a turning point (fulcrum).
A lever is used to move or lift things.
Vocabulary: machine, lever, lever arm, bar, fulcrum, turning point
- ruler (lever arm)
- rectangular eraser (fulcrum)
- pennies (load)
- Have students place a ruler (lever arm) on top of an eraser (fulcrum) so that the eraser is under the middle of the ruler. (The ruler will be balanced.)
- Have students stack 5 pennies on one end of the ruler.
- Challenge the students to raise the pennies without touching the pennies. (They need to press down on the opposite end of the ruler.)
- (Explain that the ruler is acting as a lever when they press down on the other end and it lifts the pennies.)
- Try the same activity but place the 5 pennies on the other end of the ruler.
- Challenge the students to raise the pennies without touching them.
- Have the students explain why they were able to lift the pennies without touching them.
- Have the students place 3 pennies on one end of the ruler.
- Ask them to predict the minimum number of pennies that would have to be placed on the other end of the ruler to raise the 3 pennies. (They could write down their prediction.) (Answer: 3)
- Have the students add pennies to the other side to test their prediction.
- Were they correct? Why?
- Try the same experiment with 7 pennies.
- Have students place 3 pennies on one end of the ruler and 6 pennies on the other end of the ruler.
- Challenge the students to lift the end with 3 pennies without adding or taking away pennies on either end.
- If students are having trouble tell them that they can move the pennies but must keep 3 on one side of the ruler and 6 on the other side of the ruler.
This can be accomplished by moving the heavier pile of pennies towards the fulcrum.
- Have students sketch/draw and label a seesaw (including the bar/lever arm and turning point/fulcrum.
- Have students sketch pictures of today's 3 previous lever activities in their science notebooks and explain how the lever worked in each activity.
- Have students visit a park and enjoy a real seesaw (a lever)! Have fun!
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