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Changing Rocks
Examples of Student Work

Grade 5-8 Performance Task
Contributed by: New York State Education Department (NYSED)
NYS Alternative Assessment in Science Project (1996)

Student #1


In nature, rocks are changed by abrasion due to movements by streams, glaciers, and wind. In this task, you will be using a model to study some of the effects of this abrasion. You will be observing and recording some of these effects and making generalizations and predictions.


  • 10 rocks
  • plastic jar
  • water
  • test card [laminated or plastic covered]
  • paper towels
  • metric ruler
  • plastic spoon



  1. Place one rock on the test card in the 0 shakes circle.
  2. Put the 9 remaining rocks in the jar.
  3. Fill the jar about half-full with water and close the lid tightly.
  4. Shake the jar VIGOROUSLY 50 times. Remove one rock, dry it, and place it on the test card in the 50 shakes circle.
  5. Shake the jar VIGOROUSLY another 50 times. Remove one rock, dry it, and place it on the test card in the 100 shakes circle.
  6. Repeat step 5, shaking VIGOROUSLY, removing a rock after 150, 200, 250, and 300 shakes.
  7. Look carefully at all of your rock samples on the test card.
  8. Using the graph below, draw a line representing the relationship between the number of shakes and the "amount of rounding" of the rocks. Be sure to carefully label both axes.

9. Using complete sentences, write a statement that describes what happened to a single rock as it went from 0 to 300 shakes.

10. In the space below, draw a sketch of the size and shape of the rock after 300 shakes. Predict and sketch what the size and shape of the rock would be after 600 shakes.


a. In the space below, use one or more complete sentences to describe what you think a rock will look and feel like after 600 shakes.

b. Using complete sentences, support your prediction with observations from this activity.

12. All of the rocks you have been shaking have changed in some way. Describe at least two ways the rocks and pieces at the bottom of the jar have not changed.

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