Saturday, May 7, 2011

What is a Lever?

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.

Example: seesaw




Vocabulary: machine, lever, lever arm, bar, fulcrum, turning point



Materials

  • ruler (lever arm)
  • rectangular eraser (fulcrum)
  • pennies (load)


    Activity 1




      Directions

      • 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.


      Activity 2





      Directions

      • 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.


      Activity 3






      Directions
       
      • 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.



      Activity 4


      • 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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      1 comment:

      1. Love it with a ruler! We just did this with a piece of left over wood trim and the boys matchbox cars haha!

        ReplyDelete

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