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Changing Rocks
Administration Procedures

Grade 5-8 Performance Task
Contributed by: New York State Education Department (NYSED)
NYS Alternative Assessment in Science Project (1996)
Credit/Source: Rock Recipe: Ted Anderson; Pembroke High School
Earth Science Supplement (1970) - Rock Abrasion


Students will shake a box containing Plaster of Paris "rocks", gravel, and sand, to measure the effects of erosion.

This task assesses students' abilities to make simple observations, describe observed changes, make predictions of change using observations and a model, and representing direct relationships using line graphs.

This task is designed to take students approximately 30 minutes to complete.

Overall Task Content Area:

Earth Science

Specific Knowledge Areas:

Structure of the earth system

Performance Expectations:

  • conducting investigations
  • gathering, organizing, and representing data
  • formulating conclusions from investigational data
  • applying scientific principles to develop explanations and solve new problems

National Science Education Standards:

8 A SI 1: Abilities necessary to do scientific inquiry
1.4 Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description providing causes for effects and establishing relationships based on evidence and logical argument. This standards requires a subject knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.

1.5 Think critically and logically to make the relationships between evidence and explanations. Thinking critically about evidence includes deciding what evidence should be used and accounting for anomalous data. Specifically, students should be able to review data from a simple experiment, summarize the data, and form a logical argument about the cause-and-effect relationships in the experiment. Students should begin to state some explanations in terms of the relationship between two or more variables.

1.8 Use mathematics in all aspects of scientific inquiry. Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions; to gather, organize, and present data; and to structure convincing explanations.

8 D ESS 1: Structure of the Earth System
1.3 Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National Council of Teachers of Mathematics:

Algebra (AL1): Understand patterns, relations and functions.

Problem Solvign (PS2): Solve problems that arise in mathematics and in other contexts.

General Instructions to the Teacher:

This task is designed to take students approximately 30 minutes to complete.

Students will be working individually during this exercise.

Students should be ready to work as soon as the period begins. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for "Changing Rocks":

The teacher will need:

  • 1-5 lb bag of Plaster of Paris
  • 500 ml of fine gravel
  • 500 ml sand
  • 2 or 3 aluminum (13" x 9") trays
  • water - to mix
  • hammer (to break up the rocks into smaller pieces
  • bucket to mix plaster
  • laminated test card
  • newspaper
  • small baggies or plastic containers

At this station students should have:

  • 10 rocks
  • 1 plastic jar (recommended large mouth peanut butter jars)
  • water
  • laminated test card
  • plastic spoon (to remove rocks from jar)
  • paper towels
  • metric ruler

Advance Preparation:

***Rocks should be prepared two (2) days prior to the test. ***

  1. Mix: plaster, sand, gravel, water to a pudding consistency.
  2. Pour into tray to height of 2-3 cm (1"); shake down so that it dries flat.
  3. When dried, place on newspaper and break into equal chunks of about 2-3 cm in size.
  4. Sort out 10 "rocks" (per student) of similar size and place in a baggie.
  5. Recommendation - laminated/plastic covered test card be taped down at the student test station.
  6. Check plastic jars for leaks - use only plastic jars to shake.


  • Be careful.
  • Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.


  • Depending on availability of materials, use different actual rock materials.
  • Data may be collected as a team and individual analysis may be done.


Rock Recipe: Ted Anderson; Pembroke High School.
Earth Science Supplement (1970) - Rock Abrasion.



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