Chapter focus
Build a fair investigation: ask a focused question, identify what to change and measure, record evidence, and use it to support a conclusion.
These are original study notes and practice questions prepared for revision. Use your assigned NCERT edition for the complete lesson, diagrams, activities, and exercise wording.
What you will learn
- Explain the main idea: Build a fair investigation: ask a focused question, identify what to change and measure, record evidence, and use it to support a conclusion.
- Use the key terms and relationships in the notes below.
- Show your reasoning and check whether an answer fits the question.
Key ideas and notes
- Observation records what is noticed; an inference is an explanation drawn from observations.
- A fair test changes one factor while keeping relevant conditions the same.
- Repeat observations where possible and report uncertainty honestly.
Worked example
To test whether light affects seedling growth, compare similar seedlings with equal water and soil, changing only light exposure.
Quick revision
Observation records what is noticed; an inference is an explanation drawn from observations.
A fair test changes one factor while keeping relevant conditions the same.
Repeat observations where possible and report uncertainty honestly.
Original practice questions
Try each question first. Open the answer to check your reasoning.
What is the independent variable in that example?
Answer: Light exposure.
Why repeat measurements?
Answer: Repeats help reveal variation and reduce the effect of chance or measurement error.
Does one result prove a universal rule?
Answer: No; evidence should be repeated and tested in other conditions.
Chapter summary
Build a fair investigation: ask a focused question, identify what to change and measure, record evidence, and use it to support a conclusion. The key ideas above give you a short revision path; practise explaining them in your own words and revisit any step you could not justify.