Variables and fair comparisons
An independent variable is deliberately changed; a dependent variable is measured.
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Scientific investigation · Grades 5–8Ask, test, observe, explain.
Learn through clear explanations, worked examples, and activities that ask you to think. Start with a lesson, try the task, then explain what you learned.
Start learning Free · No student accountsA three-lesson learning path
Repeated measurements
Measurements vary because of instruments, observers, and natural differences.
Explore the lesson →Claims, evidence, reasoning
A scientific explanation connects a claim to observations through reasoning.
Explore the lesson →Use what you learn
Each lesson includes a central idea, an example, an activity, and a question with an explained answer. Keep a notebook of your reasoning. Use the practice page to identify ideas worth revisiting.
Check your understanding →Teach with flexibility
Use these resources for a short classroom discussion, independent practice, or a small-group activity. Adjust reading support and task difficulty to your learners. Activities can be printed using your browser.
Read the teaching guide →Compare paper-airplane designs
Carry out a low-risk indoor investigation with adult permission and room to avoid people’s faces.
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