S3 Science: Scientific Investigation And Fair Tests (Paper 4 (error Clinic))

S3 Science: Scientific Investigation and Fair Tests (Paper 4 (error clinic))

2026-11-14

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Tutor Prep Guide · the steps of a scientific investigation, hypotheses and testable predictions, independent and dependent variables, controlled variables, fair tests, control groups, repeated measurements and the mean, range, percentage error, accuracy and precision

S3 Science: Scientific Investigation and Fair Tests (Paper 4 (error clinic))

This paper corrects ten common errors in scientific investigation, covering the definition of a fair test, identifying the dependent variable, the need for a control group, means and decimal places, percentage error, range, the list of controlled variables, proportional prediction, reducing error, and confusing precision with accuracy.

Direct answers　A fair test changes one variable; the dependent variable is measured; a control group is essential; a mean should not carry more decimals than the instrument can read; percentage error uses the accepted value; the range shows spread; controlled variables must all be listed; proportional prediction uses one ratio; repeating and averaging reduces error; precision is not accuracy.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S3 Science: Scientific Investigation and Fair Tests
Level	S3

02　Questions (10 items)

FoundationWhat is the definition of a fair test?
FoundationA study looks at how the hours of light affect flowering. Which is the dependent variable?
FoundationWhat is the problem with an experiment that has no control group?
IntermediateThree readings are 25.2, 25.4 and 25.1 mL. What is the mean to two decimal places?
IntermediateA length is measured as 19.6 cm while the accepted value is 20.0 cm. What is the percentage error?
IntermediateFour readings are 0.86, 0.90, 0.88 and 0.94. What is the range?
ChallengeWhen comparing two fertilisers, what variables must be controlled besides the type of fertiliser?
ChallengeA spring stretches 2.4 cm under 4 N. What stretch is expected under 10 N?
ChallengeWhat is the most direct way to reduce measurement error?
Error redoA student says that three identical readings from the same thermometer prove the result is accurate. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	An experiment in which only one variable is changed and all the others are kept the same	The definition needs both parts: one variable changed, everything else unchanged.
2	The time taken to flower or the number of flowers	The dependent variable is what is measured; the hours of light are the independent variable that is changed.
3	You cannot tell whether the result comes from the variable you changed	Without a baseline for comparison, changes caused by other factors get credited to the wrong variable.
4	25.23 mL	The three values add to 75.7 and divide by three to give 25.233, which rounds to 25.23.
5	2.0 percent	The error of 0.4 divided by the accepted 20.0 and multiplied by one hundred.
6	0.08	Subtract the smallest reading 0.86 from the largest 0.94.
7	The light, the water, the soil, the plant variety and the size of the pot	Every condition that affects growth must be identical, otherwise it is not a fair test.
8	6.0 cm	Divide 2.4 by 4 to get 0.6 cm per newton, then multiply by 10.
9	Repeat the measurement and take the mean	Repeating spreads and cancels the random scatter in the readings.
10	Precision is not accuracy; a faulty instrument can give identical readings that are all away from the true value	Very close readings only show high precision; accuracy needs a comparison with the accepted value.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

For any investigation ask three questions: what is changed (independent variable), what is measured (dependent variable), and what must stay the same (controlled variables); two changes at once means it is not a fair test.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.