RockLicker · Grade 4 · Lesson 2 of 5

One Change in an Erosion Model

Identify a changed variable, compare repeated model data and describe limits of the conclusion.

  • Grade 4
  • 45 minutes
  • Worksheet + teacher guidance
Back to Grade 4

What you will learn

A fair comparison changes one main factor while keeping other important conditions similar. Repeated measurements help reveal variability.

Words to use

  • variable: a factor that can change
  • trial: a repeated test
  • fair comparison: a test with controlled conditions

Evidence for this lesson

Illustrative model data, not field measurements: Low-slope movement distances: 8, 10, 9 cm. Steeper-slope distances: 18, 21, 20 cm. Same tray size, same sand amount, 100 mL water per trial.

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

Work through the activity

  1. 5 min · Read the setupTwo trays use the same sand amount, tray size and 100 mL water pour. Only tray slope differs. Identify the changed factor and the kept-similar conditions.
  2. 15 min · Compare trialsWrite the three movement distances for each slope. Find the smallest and largest in each set. Do not compare only one favorable result.
  3. 15 min · ExplainDescribe the pattern using all six values. Write a conclusion about this model under these conditions rather than every hillside.
  4. 10 min · ImproveName a possible source of measurement variation and one way to improve the next set of trials.
RockLicker
GRADE 4 · LESSON 2

One Change in an Erosion Model

Draw on the printed sheet or write, type or dictate your response.
Draw on the printed sheet or write, type or dictate your response.
Draw on the printed sheet or write, type or dictate your response.
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 factor was deliberately changed?

Teacher & family guide · answers and assessment

Grade 4 · One Change in an Erosion Model

Learning goal: Identify a changed variable, compare repeated model data and describe limits of the conclusion.

Expected responses

  1. Slope changed; sand amount, tray size and water volume stayed similar.
  2. Low slope 8–10 cm; steeper slope 18–21 cm.
  3. The steeper tray moved sediment farther in every supplied trial.
  4. Pour rate, grain mixture and measurement precision may matter; repeat or control them better.

Understanding check: Tray slope. The stated comparison changes slope while keeping water volume and sand amount similar.

Watch for this misconception

The model pattern does not establish a universal erosion rate or prove slope was perfectly isolated.

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. Draw a dot plot with one dot for every trial rather than only the largest value.