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California CAST · Grade 8 · Science

California Grade 8 CAST Science Practice Test

Build Grade 8 California CAST Science readiness with five focused 10-question practice sets covering life science, physical science, Earth and space science, engineering, and environmental data.

Grade 8 CAST Science practice sets

This California Grade 8 CAST Science Practice Test page provides five short practice sets with 10 original multiple-choice questions each. The sets support supplemental review across life science systems, heredity, physical science, Earth and space processes, engineering practices, environmental systems, and data analysis.

Science skills covered

  • Cell transport, cell division, heredity, natural selection, genes and proteins, ecosystems, reproduction, mutations, common ancestry, and adaptation
  • Conservation of matter, gas particles, motion, energy, thermal transfer, circuits, physical and chemical change, forces, friction, and waves
  • Earthquakes, plate boundaries, rocks, ocean currents, Moon motion, paleoclimate, water cycle, seasons, and glaciers
  • Controlled variables, models and limitations, engineering trade-offs, reaction data, reliable measurement, prototypes, and scientific explanations
  • Drought, urban heat, pollution, invasive species, recycling, groundwater, populations, biodiversity, carbon emissions, and seasonal data

How to use this page

Complete one 10-question set at a time. Identify the evidence, describe the mechanism, and review every explanation before moving to the next set.

This is supplemental State Test Practice, State Assessment Practice, and Standardized Test Practice. It does not replace current California Department of Education guidance, official CAST blueprints, accommodations, or testing schedules.

For the broader California assessment hub, visit California State Assessments.

Select a test

5 Tests
1. Test2. Test3. Test4. Test5. Test

4. Test

California Grade 8 CAST Science Practice Questions

A 10-question California Grade 8 CAST Science practice set on engineering and scientific practices, with answers and explanations.

Read each science task carefully, choose one answer, and review the explanation after responding.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

An engineer designs a water filter. Which test provides the strongest evidence of performance?

Please select an answer first.

Correct answer: A

The correct answer is Measure the clarity and particle levels of water before and after repeated trials..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Repeated before-and-after measurements directly evaluate the filter’s function.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Repeated before-and-after measurements directly evaluate the filter’s function.

2. QuestionMultiple choice

A student changes both the amount of light and the amount of water given to plants. Why is this design difficult to interpret?

Please select an answer first.

Correct answer: B

The correct answer is Two independent variables changed, so their separate effects cannot be identified..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Changing two factors at once prevents a clear comparison of each factor’s effect.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Changing two factors at once prevents a clear comparison of each factor’s effect.

3. QuestionMultiple choice

A model predicts that increasing insulation will lower heat loss. Which evidence would support the model?

Please select an answer first.

Correct answer: C

The correct answer is Identical containers with more insulation show a larger temperature decrease over the same time..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Controlled temperature data connecting insulation amount with heat loss support the prediction.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Controlled temperature data connecting insulation amount with heat loss support the prediction.

4. QuestionMultiple choice

Why should a scientific model identify what it does not include?

Please select an answer first.

Correct answer: D

The correct answer is Stating limitations helps users understand when the model may not apply..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Models simplify systems, so identifying limits helps interpret their predictions responsibly.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Models simplify systems, so identifying limits helps interpret their predictions responsibly.

5. QuestionMultiple choice

An engineer chooses a material that is strong but expensive. What trade-off is being considered?

Please select an answer first.

Correct answer: A

The correct answer is Strength versus cost..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Engineering decisions often balance performance with available resources and cost.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Engineering decisions often balance performance with available resources and cost.

6. QuestionMultiple choice

A graph of a reaction shows that the rate increases as temperature rises, then levels off. What question would help explain the pattern?

Please select an answer first.

Correct answer: B

The correct answer is Does another factor limit the reaction at higher temperatures?.

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: A leveling pattern suggests that another limiting factor may control the rate at higher temperatures.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

A leveling pattern suggests that another limiting factor may control the rate at higher temperatures.

7. QuestionMultiple choice

What makes a measurement more reliable?

Please select an answer first.

Correct answer: C

The correct answer is Repeating it with a calibrated tool and consistent procedure..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Repeated measurements with a consistent, calibrated method improve reliability.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Repeated measurements with a consistent, calibrated method improve reliability.

8. QuestionMultiple choice

A student claims that a shaded surface is cooler than an unshaded surface. Which evidence is most useful?

Please select an answer first.

Correct answer: D

The correct answer is Temperature readings from both surfaces taken at the same times and locations..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Comparable temperature readings directly test the claim.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Comparable temperature readings directly test the claim.

9. QuestionMultiple choice

Why do engineers build a small prototype before constructing a full-size structure?

Please select an answer first.

Correct answer: A

The correct answer is The prototype can reveal weaknesses with less cost and risk..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Small-scale testing helps identify problems and guide revisions before full construction.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Small-scale testing helps identify problems and guide revisions before full construction.

10. QuestionMultiple choice

A scientific explanation says that one variable caused another but gives no data. What is missing?

Please select an answer first.

Correct answer: B

The correct answer is Evidence and reasoning connecting the data to the claim..

  1. Identify the science idea: Determine whether the task focuses on life, physical, Earth and space, engineering, or systems science.
  2. Use the evidence: Claims about cause require evidence and reasoning that address alternative explanations.
  3. Check the choice: Make sure the answer explains the mechanism, pattern, or evidence rather than only repeating a detail.

Claims about cause require evidence and reasoning that address alternative explanations.

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Frequently asked questions about California Grade 8 CAST Science Practice Test

Which Science skills are covered?

The page covers Grade 8 life science, physical science, Earth and space science, engineering practices, environmental systems, and data analysis.

How many questions are included?

There are five practice sets with 10 questions each, for 50 questions in total. Each set can be completed separately.

Are these official CAST questions?

No. These are original supplemental practice questions. Check the latest California Department of Education information for official materials, standards, accommodations, and policies.