Lesson 3 of 3 · Scientific investigation

Claims, evidence, reasoning

Suggested time: 15–25 minutes

The idea

A scientific explanation connects a claim to observations through reasoning. Evidence reports what was measured; reasoning explains why it supports the claim. Conclusions should stay within the limits of the investigation. Correlation alone does not establish a cause.

Worked example

If shaded plants grew less in a controlled study, report the measurements before suggesting a relationship with light. Avoid claiming that every plant species will respond identically.

Another application

A plane flew farther in four trials under one indoor launch method. This supports a limited claim about those trials. Additional launches, builders, and conditions would help test whether the result is robust.

A common misunderstanding

A conclusion should not imply that a small study proves a universal law. Describe the tested conditions and recognize other possible explanations.

Try it yourself

Write a conclusion using three labeled parts: claim, evidence, and reasoning. Add one limitation and one useful follow-up question.

Check your understanding

Does “my design is best” count as evidence?

Reveal the explained answer

No. It is a claim; evidence would include relevant observations or measurements.

Try the practice questions