Asking scientific questions & forming hypotheses

Good scientific investigations start with a clear, testable question — one that can actually be answered by collecting data, like "Does the amount of sunlight affect how fast a plant grows?" rather than a vague question like "Are plants good?". A hypothesis is a reasoned prediction about the answer, based on existing knowledge, often written as an "if...then..." statement. A hypothesis isn't just a guess — it should be based on reasoning or prior evidence, and importantly, it must be testable, meaning an experiment could actually prove it right or wrong.

Key terms

Testable question:

A question specific enough that it can be answered by collecting and analysing data.

Hypothesis:

A reasoned, testable prediction about the answer to a scientific question, often written as an "if...then..." statement.

Questions

1. 1. A good scientific question should be:

   • Vague
   • Testable and specific
   • Impossible to answer
   • About opinions only

2. 2. A hypothesis is:

   • A random guess
   • A reasoned, testable prediction
   • A proven fact
   • A type of graph

3. 3. "Are plants good?" is a:

   • Good testable question
   • Too vague to investigate
   • Perfectly specific
   • The best possible question

4. 4. "Does sunlight affect plant growth?" is a:

   • Vague, untestable question
   • A more testable, specific question
   • Impossible to research
   • About opinions

5. 5. A hypothesis is often written as:

   • A single word
   • An "if...then..." statement
   • A drawing only
   • A random number

6. 6. A hypothesis should be based on:

   • Nothing at all
   • Reasoning or prior evidence
   • Pure guessing with no basis
   • Random chance

7. 7. For a hypothesis to be useful, it must be:

   • Impossible to test
   • Testable
   • Always already known to be true
   • Unrelated to the question

8. 8. Which is the more testable, specific version of "Are plants good?"

   • Do plants exist?
   • Does the amount of sunlight affect how fast a plant grows?
   • Plants are nice.
   • None of these

9. 9. Which is a properly structured hypothesis?

   • Plants like sunlight
   • If a plant receives more sunlight, then it will grow taller, because sunlight provides energy for photosynthesis
   • Sunlight is yellow
   • Plants are green

10. 10. A hypothesis differs from a random guess because it:

    • Has no reasoning behind it
    • Is based on reasoning or existing evidence
    • Is always correct
    • Cannot be tested

11. 11. Which question is testable?

    • Is science interesting?
    • Does adding fertiliser increase plant height over 4 weeks?
    • Is nature beautiful?
    • Are plants happy?

12. 12. A testable question generally allows you to:

    • Never collect any data
    • Collect data to actually answer it
    • Only give an opinion
    • Avoid an experiment entirely

13. 13. Which is NOT a good scientific hypothesis?

    • If temperature increases, then the reaction rate will increase, because heat adds energy to particles
    • Chemistry is my favourite subject
    • If a plant gets less water, then it will wilt, because water is needed for cell structure
    • If more force is applied, then the object will accelerate more, because force causes acceleration

14. 14. Forming a hypothesis before an experiment mainly helps you:

    • Know exactly what to test and expect, based on reasoning
    • Avoid doing any experiment at all
    • Guarantee the result will be correct
    • Skip collecting data

15. 15. A student hypothesises "If I water a plant with orange juice, then it will grow faster, because juice tastes nice." What is the main flaw?

    • It isn't testable
    • It has no scientific reasoning connecting the cause to the predicted effect
    • It has too much detail
    • It doesn't use an if-then structure

16. 16. Why must a hypothesis be falsifiable (able to be proven wrong by evidence)?

    • So it can be blindly believed regardless of results
    • So that an experiment can actually test whether it holds up against evidence
    • Falsifiability is unimportant in science
    • So it can never be tested

17. 17. A student wants to investigate "Does more study time improve test scores?" Which is the best hypothesis?

    • Studying is good
    • If students study more hours per week, then their test scores will increase, because more practice reinforces learning
    • Test scores don't matter
    • Some students like studying

18. 18. Why is "Do plants like music?" a weaker scientific question than "Does exposure to music affect plant growth rate?"?

    • The first cannot be objectively measured or tested in the same clear way as the second
    • Both are equally testable
    • Plants cannot be studied scientifically at all
    • Music has nothing to do with science

19. 19. A hypothesis is tested and found to be incorrect. What does this mean for the scientific process?

    • The scientist failed completely and should stop
    • This is a normal, valuable part of science — the result still provides useful information
    • It means the question was invalid
    • Failed hypotheses are hidden and never reported

20. 20. Why is it useful to base a hypothesis on prior knowledge or reasoning rather than a random guess?

    • It gives a scientifically grounded prediction to test, making the investigation more meaningful
    • Random guesses are always more accurate
    • Prior knowledge makes experiments unnecessary
    • Reasoning has no role in hypotheses