RockLicker · Grade 8 · Lesson 5 of 5

Design a Geology Investigation

Design a fair comparison, analyze repeated data and communicate a bounded conclusion.

Grade 8
60 minutes
Worksheet + teacher guidance

What you will learn

A useful investigation connects a question, measurable variables, consistent methods, repeated observations and a conclusion proportionate to the evidence. A model can test a specific relationship without proving every natural case.

Words to use

independent variable: deliberately changed factor
dependent variable: measured outcome
replicate: repeated trial

Evidence for this lesson

Illustrative data: slope A travel distances 9, 10, 11 cm; slope B 18, 20, 22 cm. Same stated tray, sediment amount and water volume. Pour-rate consistency was not recorded; this is a possible confounder.

Use the supplied record as written; do not invent missing results.

Work through the activity

10 min · Define a questionAsk how two specified slopes affect sediment travel in a tray model. Name slope as the changed factor and travel distance as the outcome.
20 min · Analyze dataCompute each set’s mean and range. Compare all trials. Describe the observed difference without hiding the variation.
20 min · Design the next testSpecify tray dimensions, material amount, water volume, pour rate, slope measurement and distance rule. Include at least three fresh trials per condition and adult cleanup.
10 min · Write a reportState the model conclusion, one remaining confounder and one additional test. A partner checks whether your claim exceeds your data.

GRADE 8 · LESSON 5

Design a Geology Investigation

Learner / team

Date

1. State the question, changed factor and measured outcome.Draw on the printed sheet or write, type or dictate your response.

2. Compute each mean and range.Draw on the printed sheet or write, type or dictate your response.

3. Write a repeatable next-test plan with three controlled conditions.Draw on the printed sheet or write, type or dictate your response.

4. Write a conclusion and one limit.Draw on the printed sheet or write, type or dictate your response.

Responses stay in this open page only. Print before closing or changing pages; no student record is stored online.

Check your understanding

Which conclusion fits the supplied trials?

Choose an answer. You can revise after reading the explanation.

Teacher & family guide · answers and assessment

Grade 8 · Design a Geology Investigation

Learning goal: Design a fair comparison, analyze repeated data and communicate a bounded conclusion.

Expected responses

Question compares two slopes; independent variable slope; dependent variable sediment travel distance.
Slope A mean 10 cm, range 9–11 cm; B mean 20 cm, range 18–22 cm.
Accept a precise plan holding material, tray, water amount and pour method consistent, with replication and a measurement rule.
B traveled farther in these trials; a model-specific conclusion is supported, not a universal field erosion rate.

Understanding check: Slope B produced greater travel in this model. The data compare model travel distances, not universal field rates.

Watch for this misconception

Repeats improve evidence but do not remove a systematic confounder shared by every trial.

Assess the evidence

Look for the observations, calculation or explanation named in the learning goal. Accept accurate drawings and dictated responses. Use the expected responses to discuss reasoning; a correct guess without explanation is a starting point for another conversation.

Adapt and extend

Read prompts aloud, enlarge print or let a partner record the learner’s explanation. Plan a second experiment that changes only pour rate, keeping slope fixed.