Exploring the Investigative World of Science – Class 8 Science notes, important questions and MCQs

Chapter overview

Scientists investigate by observing, asking questions, predicting, testing fairly and drawing conclusions from evidence.

Steps of an investigation

• Observe and ask a question that can be tested.
• Make a prediction (hypothesis) and plan a fair test.
• Collect data, look for patterns, and conclude; share results so others can check them.

Good practice

• Change one variable, measure one, keep the rest the same.
• Repeat measurements and take the average.
• Record honestly — unexpected results are also useful.

Key terms

Variable

something that can change in an experiment

Evidence

observations and data that support or reject an idea

Controlled variable

a factor kept the same in an experiment so the test is fair

Formulas

• Investigation: question → hypothesis → test → data → conclusion

Important questions with answers

Quick revision

• Fair test = one change at a time.
• Repeat for reliable results.
• Science ideas can change with new evidence.

Exam tips

• Name the independent, dependent and controlled variables in experiment questions.
• Use tables with units in the heading.

Practice MCQs

1. A prediction that can be tested is a

   1. conclusion
   2. result
   3. hypothesis
   4. table
   Show answer

   Answer: (c) hypothesis. Hypothesis.

2. Results should be

   1. hidden
   2. changed to match
   3. recorded honestly
   4. guessed
   Show answer

   Answer: (c) recorded honestly. Honest records.

3. In testing whether salt affects the boiling point of water, the variable you change is

   1. temperature
   2. type of pot
   3. amount of salt
   4. time
   Show answer

   Answer: (c) amount of salt. Independent variable.

4. Why repeat an experiment?

   1. to save time
   2. to change the question
   3. to make results reliable
   4. to avoid measuring
   Show answer

   Answer: (c) to make results reliable. Reduces chance errors.

5. In testing whether temperature affects how fast sugar dissolves, the dependent variable is

   1. temperature
   2. amount of water
   3. time taken to dissolve
   4. type of cup
   Show answer

   Answer: (c) time taken to dissolve. What we measure.

6. A student tests plant growth with two fertilisers but gives one plant more sunlight. The test is

   1. unfair, because two variables changed
   2. fair
   3. fair if repeated
   4. always valid
   Show answer

   Answer: (a) unfair, because two variables changed. Light and fertiliser both changed.

7. A result that does not match your prediction means

   1. the hypothesis may need changing
   2. the experiment is useless
   3. you should hide it
   4. science has failed
   Show answer

   Answer: (a) the hypothesis may need changing. Evidence guides ideas.

8. A student gets different results each time. The best next step is

   1. change the conclusion
   2. stop the experiment
   3. repeat the experiment and check for errors
   4. copy a friend's result
   Show answer

   Answer: (c) repeat the experiment and check for errors. Reliability.