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Task with Student Directions

4th Grade Performance Task
Contributed by: Kentucky Department of Education (KDE)
Performance Events 1993-94


Students will experiment with a pendulum to find out why it might swing at different speeds at different times.

This task is designed to take approximately 30 minutes.


  • Information sheet
  • Three weights
  • Pencils
  • Three wires
  • Bar

Group Activity:

Marcia and Kevin were swinging on the playground. They timed their swings and found that Kevin made more swings in 15 seconds than Marcia did. Why would that happen? Was it a difference in their weights? Were their swings different in length?

Your job is to experiment with the pendulum at your table to find an explanation for why Marcia and Kevin were swinging at different rates.

First read the sheet at your table called "Information Sheet-How to Use the Pendulum."



Experiment with the pendulum by doing the tests described. There are two variables you will change as you work. (Things that can change are called variables.) The variables are length of the wire and weight of the bob.

You will change only one variable at a time. Each time you change a variable. YOU COUNT THE NUMBER OF COMPLETE SWINGS THE PENDULUM MAKES IN 15 SECONDS. Do each test twice (Trial 1 and Trial 2). Each member of the group should record the results of the tests in the tables below.

  1. Use the charts below to record your measurements. Always give the number of COMPLET SWINGS THE PENDULUM MAKES IN 15 SECONDS.

    VARIABLE 1: USING DIFFERENT LENGTHS (Use only the largest weight.)
    Long Wire
    Medium Wire
    Short Wire
    Trial 1
    Trial 2

    VARIABLE 2: USING DIFFERENT WEIGHTS (Use only the longest wire.)
    Large Weight
    Medium Weight
    Small Weigth
    Trial 1
    Trial 2

  2. Work together as a group to study your results. Then write what the group thinks is the reason Marcia and Kevin did not swing at the same rate.


Individual Activity:

  1. What happened to the rate the pendulum swung when you changed the length of the wire?

  2. What happened to the rate the pendulum swung when you changed the amount of weight that was swinging?

  3. Which variable most affected the number of swings in 15 seconds?

  4. If Marcia and Kevin wanted to be sure that they would swing at almost exactly the same rate, what thing or things would they have to change before they tried swinging again?

  5. The pendulum system is a model of the swing system. Compare the parts of the two systems.



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