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Specimen lab book: Reaction time
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Study Hack Lab
RP 7 · Biology
Reaction time
Lab book
Name
Specimen
Date
2 November 2026
Course
GCSE Biology
Board and specification
AQA GCSE Biology (8461), 4.5.2.1AQA GCSE Combined Science: Trilogy (8464), 4.5.2Apparatus and techniques: AT 1, AT 3, AT 4
Run
C29HO
Status
Finished: every stage done
Exam questions
30/30 marks
Aim
Plan and carry out an investigation into the effect of a factor on your reaction time, using the ruler-drop test.
Contents
Plan and risk assessment
Apparatus
Method
Results
Graph
Analysis
Conclusion and evaluation
Make safe and clear up
Exam questions on your data
Simulated data produced by Study Hack Lab from the student's own run (seed 20261004). Every reading, value and mark here is from that run; nothing has been retyped. Layout v1, practical v2. Original material; not affiliated with AQA, which has not reviewed it.
1 Plan and risk assessment
You see the ruler move (receptor: the eye), a nerve impulse travels along a sensory neurone to the brain, which decides to catch, then along a motor neurone to the muscles of your thumb and finger (effectors). Meanwhile the ruler falls from rest, d = ½gt², so the distance it falls before you catch it measures your reaction time. With d in cm, g = 980 cm/s².
t = √(2d / g)
Variables
Independent (you change)
The factor you chose
Dependent (you measure)
Reaction time in s
Control (you keep the same)
Starting position of the ruler; Gap between thumb and finger; Arm position; Same catcher and same dropper; No warning; Same hand; Same conditions for the catcher; Caffeine: the drink and the wait
Prediction
About how far will the ruler fall before you catch it?
About 10–25 cmRight first time
Your median catch was 20.5 cm. A reaction time of about 0.15–0.22 s lets the ruler fall about 11–24 cm (d = ½gt²). A catch of 1–3 cm would mean a reaction faster than nerve impulses can travel.
You will choose one factor to test when you collect your apparatus: practice, which hand, a distraction or caffeine. How do you expect a factor like these to change reaction time?
Shorter after practice, with the dominant hand, without distraction, or after caffeine: by a few hundredths of a second.Right first time
Attempts 1–5: 207 ms. Attempts 6–10: 199 ms. Shorter, as you predicted, though the ranges overlap, so the difference could be due to chance. Practice and using your dominant hand let the brain coordinate the response faster; a distraction gives the brain a second task; caffeine is a stimulant. The differences are small, so compare them with the spread of your repeats.
Is catching the ruler a reflex action?
No. You see the ruler move and your brain decides to close your fingers.Right first time
Reflexes are automatic and do not involve the conscious part of the brain. Catching the ruler is a conscious response: eye (receptor) → sensory neurone → brain → motor neurone → finger muscles (effector).
Risk assessment
Hazard
Harm it could cause
Control you chose
A dropped metre rule
Eye injury to the person dropping it if it bounces off the floor
The person dropping wears safety goggles; hold the ruler over the table, not over a gap.Right first time
Testing people
Discomfort or embarrassment about slow results
Take part only with consent and stop at any time; record results under a code, never rank people by name.Right first time
A caffeinated drink (caffeine factor only; virtual in this lab)
Raised heart rate, anxiety or poor sleep; a reaction in someone with a heart condition or an allergy
Teacher and parental permission; check medical conditions and allergies first; one can of cola at most; drink it outside the laboratory, never in it.Right first time
Sitting on a chair at the edge of the table
Falling off the chair while reaching for the ruler
Sit upright and back on the chair; catch with your fingers only, do not lunge for a missed ruler.Right first time
2 Apparatus
✓Metre rule (resolution 1 mm (read to 0.5 cm at the thumb)) Dropped and caught: the distance it falls measures your reaction time.
✓Chair and table Sit upright with your forearm resting on the table.
✓Safety goggles For the person dropping the ruler.
✓Conversion table Converts the distance fallen to a reaction time.
✓Results table and pencil Record every catch as you go.
✓Your catching hand and a partner Your partner holds the rule at the top and drops it with no warning. You catch it with your thumb and first finger.
3 Method: your choices
Your factor: Practice: does reaction time get shorter over 10 attempts in a row? (the AQA handbook’s investigation)Ten drops in a row with your weaker hand. You plot reaction time against attempt number.
Put goggles on the person who drops the rulerSafety: DoneA dropped metre rule can bounce off the floor and up into the face of the person dropping it.
Rest your arm: Forearm flat on the table, hand over the edgeYour hand starts in the same place every time.
Choose the gap between thumb and finger: A 2 cm gap every timeClosing your fingers adds the same small time to every catch.
Choose where the ruler starts: Line the zero up with the top of the thumb before every dropEach reading is the distance the ruler fell.
Choose whether to practise before you start: No practice: record every catch from the first oneYour first few catches show any learning effect.
When the ruler is dropped: No warning, after a random waitYou react to seeing the ruler move.
Where to read the ruler: The mark level with the top of the thumbEach reading is the distance the ruler fell.
4 Results
10 of 10 readings taken.
Ten attempts with the weaker hand · Recorded from the very first catch. The reaction time for attempt 2 is left blank: you convert that one yourself in Analyse.
Attempt
Ruler reading in cm
Reaction time in s
1
23.5
0.219
2
21.0
0.207
3
20.5
0.205
4
19.0
0.197
5
21.0
0.207
6
20.5
0.205
7
20.0
0.202
8
3.0, crossed out,19.5
0.199
9
21.5
0.209
10
15.5
0.178
Means · Leave out any anomalous catch. The mean reaction time is worked out from the mean distance.
Attempts
Mean ruler reading in cm
Mean reaction time in ms
Attempts 1–5
21.00
207
Attempts 6–10
19.40
199
0.0 Struck through: the anomaly, retaken; the new reading is beside it.
Anomaly: Attempt 8, retaken. Likely cause: the catcher guessed when the ruler would drop and closed early (anticipation): too fast to be a reaction.
5 Graph
This practical has no graph: the results are in the table above.
6 Analysis
Convert a reading to a time
Find the distance in the conversion table and read the reaction time beside it.
Use the conversion table to find your reaction time for attempt 2 (21.0 cm).
0.207 sRight first time
Mean ruler reading
mean = sum of the readings ÷ number of readings
Calculate the mean ruler reading for attempts 6–10.
19.4 cmRight first time
Mean reaction time (Higher)
t = √(2d / g), with d in cm and g = 980 cm/s²
Use your mean ruler reading to calculate your mean reaction time for attempts 6–10. Give your answer in milliseconds to 3 significant figures.
199 msRight first time
Show your results
Line graph: reaction time against attempt numberRight first time
7 Conclusion and evaluation
Quantity
Your value
Accepted value
Mean reaction time for attempts 6–10 (your own reaction time, careful technique)
199 ms
197 ms
Conclusion
Which conclusion do your results support best?
My reaction time got shorter over the first few attempts, then levelled off.Right first time
Your first two attempts were 2.9 cm longer on average than attempts 6–10. The brain gets better at the task with practice: the first attempts are slowest, and after about five the times level off. With one person only, you cannot say it is true for everyone.
Sources of error
Zero not level with the top of the thumb at the start: systematic or random?
SystematicRight first time
Every reading is out by the same 1–2.5 cm, so every reaction time is too short or too long.
Reading at the bottom of the thumb: systematic or random?
SystematicRight first time
Every reading is 2.0 cm too small, so every reaction time is too short.
Warning the catcher before the drop: systematic or random?
SystematicRight first time
The catcher times the catch: every time is too short, and anticipation catches are more likely.
Thumb and finger opened wide: systematic or random?
SystematicRight first time
The fingers take longer to close, so every catch is about 1–2 cm too long.
Arm not supported: systematic or random?
RandomRight first time
The hand moves up and down between and during catches, so the readings scatter more.
Getting quicker with practice during the record: systematic or random?
SystematicRight first time
The first, unpractised catches are longer. If they all fall in one condition, that condition looks slower than it is.
Natural variation from one catch to the next: systematic or random?
RandomRight first time
No two catches are the same, so a difference between conditions may be due to chance.
Only one person tested: systematic or random?
RandomRight first time
One person’s results may not be typical, so the conclusion cannot be applied to everyone.
Improvement
Which change would most improve your results?
Do more drops in each condition and compare the means with the spread.Right first time
Repeatable or reproducible
Your attempts 6 to 10 (same person, same method, same ruler) were all within 6.0 cm of each other. This shows your results are…
RepeatableRight first time
Repeatable: the same person, method and equipment give similar results.
Another student used a computer reaction test and also found practice made their reaction time shorter. This shows the results are…
ReproducibleRight first time
Reproducible: a different person, method or equipment gives similar results.
8 Make safe and clear up
Stand the metre rule back in the rack (never leave it on the floor)
Take off the goggles and return them
Give your results a code instead of a name before you share them with the class
Push the chairs back under the table
9 Exam questions on your data
On your own readings, self-marked against the mark scheme, with error carried forward where it applies. Total 30/30.
01.1[1 mark]
You investigated whether practice changes reaction time. You did ten ruler drops in a row with your weaker hand.
What was the independent variable in your investigation?
Your answer
The attempt number (how many attempts you had had: practice).
1/1 self-marked
Attempt number (the number of attempts / amount of practice)
Self-marked: 1 of 1 mark. This is your own judgement against the mark scheme.
Model answer: The attempt number (how many attempts you had had: practice).
01.2[1 mark]
The investigation tests how practice (the number of attempts) affects reaction time, using the ruler-drop test: a ruler is dropped without warning and the distance it falls before it is caught is measured.
Write a hypothesis for your investigation.
Your answer
Reaction time gets shorter as the number of attempts (practice) increases.
1/1 self-marked
Links the factor to reaction time with a direction (e.g. “reaction time is shorter with …” / “… makes reaction time longer”)
Self-marked: 1 of 1 mark. This is your own judgement against the mark scheme.
Model answer: Reaction time gets shorter as the number of attempts (practice) increases.
01.3[2 marks]
The investigation tests how practice (the number of attempts) affects reaction time, using the ruler-drop test: a ruler is dropped without warning and the distance it falls before it is caught is measured.
Give two variables you should control in your investigation.
Your answer
The zero of the ruler level with the top of the thumb each time. The same gap between thumb and finger.
2/2 self-marked
Same starting position of the ruler (zero level with the top of the thumb)
Same gap between thumb and finger
Same arm position (forearm resting on the table)
Same hand
Same person dropping / dropped the same way
No warning before the drop (random intervals)
Same ruler
Age / sex / mass of the catcher
Amount of sleep
Caffeine or other drugs beforehand
Time of day
Distractions (noise)
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: The zero of the ruler level with the top of the thumb each time. The same gap between thumb and finger.
01.4[2 marks]
Explain why catching the ruler is not a reflex action.
Your answer
It is not automatic; it is a conscious action because the brain decides to catch the ruler.
2/2 self-marked
It is not automatic (it is voluntary / conscious / you choose to do it)
It involves (the conscious part of) the brain / a decision is made by the brain
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: It is not automatic: you choose to close your fingers. The response involves the conscious part of the brain, which decides to catch the ruler.
01.5[1 mark]
Suggest why the student who drops the ruler should wear safety goggles.
Your answer
The ruler could bounce off the floor and hit them in the eye.
1/1 self-marked
The ruler could bounce (off the floor) and hit them in the eye (eye injury)
Self-marked: 1 of 1 mark. This is your own judgement against the mark scheme.
Model answer: If the ruler hits the floor it can bounce up and hit them in the eye.
02.1[1 mark]
On drop 2 you caught the ruler at 21.0 cm.
Table 1 is part of the conversion table you used.
Table 1
Distance fallen in cm
Reaction time in s
18
0.192
19
0.197
20
0.202
21
0.207
22
0.212
23
0.217
24
0.221
25
0.226
Use Table 1 to find your reaction time for drop 2.
Your answer
0.207
1/1
0.207 s
Full marks. Well done.
Model answer: 0.207 s
02.2[1 mark]
Table 2 shows your readings for attempts 6 to 10, as you first recorded them.
Which reading is anomalous?
Select one row.
Table 2
Drop
Ruler reading in cm
6
20.5
7
20.0
8
3.0
9
21.5
10
15.5
Your answer
drop 8
1/1
Drop 8 (3.0 cm): far shorter than the others, too short to be a real reaction
Full marks. That is exactly what the mark scheme is looking for. Drop 8 (3.0 cm) is far below the others: the catcher anticipated the drop.
Model answer: Drop 8. 3.0 cm is far shorter than the other readings: too fast to be a real reaction, so the catcher guessed when it would drop.
02.3[2 marks]
Look again at Table 2.
Calculate the mean ruler reading.
Do not use the anomalous result.
Your answer
19.38
Working: mean = (20.5 + 20.0 + 21.5 + 15.5) ÷ 4
= 77.5 ÷ 4
= 19.38 cm
2/2
(20.5 + 20.0 + 21.5 + 15.5) ÷ 4 (the anomaly left out)
19.38 (cm) (allow 19.4)
Full marks. That is exactly what the mark scheme is looking for.
Model answer: mean = (20.5 + 20.0 + 21.5 + 15.5) ÷ 4
= 77.5 ÷ 4
= 19.38 cm
02.4[4 marks]
Use your answer to the mean in 02.3 (or 19.38 cm).
t = √(2d / g)
d = distance fallen in cm; g = 980 cm/s²
Calculate the mean reaction time.
Give your answer in milliseconds to 3 significant figures.
Your answer
199
Working: t = √(2 × 19.375 ÷ 980)
= √0.03954
= 0.1988 s
= 198.8 ms
= 199 ms (3 s.f.)
4/4
t = √(2 × 19.38 ÷ 980) (substitution)
t = 0.1988 s
198.8 ms
199 ms (3 significant figures)
Full marks. Clear and precise.
Model answer: t = √(2 × 19.375 ÷ 980)
= √0.03954
= 0.1988 s
= 198.8 ms
= 199 ms (3 s.f.)
02.5[1 mark]
You plotted your reaction time against attempt number as a line graph.
Another student compared their mean reaction time with their dominant hand and with their weaker hand. They drew a bar chart.
Why is a bar chart the right type of chart for the other student’s results?
Tick (✓) one box.
✓ The independent variable is categoric. (your choice)
The dependent variable is categoric.
There are only two readings.
A bar chart shows the trend more clearly.
Your answer
The independent variable is categoric.
1/1
The independent variable is categoric.
Full marks. Well done.
Model answer: Which hand is used is a categoric independent variable, so the means are shown as a bar chart.
03.1[2 marks]
Figure 1 shows your reaction times against attempt number, with a curve of best fit.
Figure 1
Describe the pattern shown in Figure 1.
Your answer
The reaction time decreases as the attempt number increases, then levels off after about attempt 5.
2/2 self-marked
Reaction time decreases (gets shorter) as the attempt number increases / over the first few attempts
Then levels off (stays about the same) after about four or five attempts
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: The reaction time decreases over the first few attempts, then levels off at about the same value from about attempt 5.
03.2[2 marks]
A student says: “Practice makes reaction time shorter.”
Use your results in Figure 1.
Give one piece of evidence that supports this and one reason it may not be a valid conclusion.
Your answer
For: the reaction times got shorter over the first attempts. Against: only one person was tested.
2/2 self-marked
For: the reaction times got shorter over the first attempts (the first attempts were the slowest)
Against: only one person was tested / only a few drops / the times levelled off
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: For: the reaction times got shorter over the first few attempts. Against: only one person was tested, and the times levelled off after about five attempts.
03.3[2 marks]
Another student did the ruler-drop test with a metre rule marked only in centimetres. Their partner held the ruler roughly above the student’s open hand, which was held up in the air, and said “go” as they dropped it.
Suggest two improvements to the student’s method. Do not include repeating the test.
Your answer
Start each drop with the zero level with the top of the thumb. Rest the arm on the table.
2/2 self-marked
Start with the zero level with the top of the thumb (the same starting position)
Use a ruler with a millimetre scale (more precise; ignore "more accurate ruler")
Rest the arm (forearm) on the table
Same gap between thumb and finger
Drop without warning / at random intervals
Same hand / same person dropping
Convert the distance to a reaction time (allow: use a computer test)
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: Start each drop with the zero of the ruler level with the top of the thumb. Rest the forearm on the table. (Or: use a ruler with a mm scale; drop without warning.)
03.4[2 marks]
Another student read the ruler at the bottom of their thumb instead of the top.
Explain how this affected their results.
Your answer
Every reading is about 2 cm too small, so every reaction time is too short. It is a systematic error.
2/2 self-marked
Every reading (distance) is too small (by the thickness of the thumb, about 2 cm)
So every reaction time is too short (a systematic error)
Self-marked: 2 of 2 marks. This is your own judgement against the mark scheme.
Model answer: Every reading was about 2 cm too small, because the bottom of the thumb is lower down the ruler where the numbers are smaller. So every reaction time was too short: a systematic error.
04[6 marks]
A student wants to find out if drinking coffee affects reaction time.
They have: a metre rule, a partner, cups of coffee, a conversion table and a timer.
Plan an investigation to find out whether drinking coffee affects reaction time. Include how you would make your results valid.
Your answer
1. Use the ruler-drop test: a partner holds a metre rule with the zero level with the top of the catcher’s thumb, the thumb and finger a set gap apart and the forearm resting on the table.
2. The partner drops the ruler without warning, at random times, and the catcher catches it. Record the reading at the top of the thumb.
3. Do this 5 times and calculate the mean distance; convert it to a reaction time with the conversion table.
4. The catcher drinks a fixed volume of the same coffee (for example 200 cm³).
5. Wait the same time after drinking (for example 20 minutes), then repeat the 5 drops and calculate the new mean.
6. Compare the means with and without coffee.
7. Keep the same hand, the same person dropping, the same gap and the same time of day. Test several students of the same age, who have had no other caffeine that day.
6/6 self-marked
Ruler-drop test: a partner holds the ruler (zero) level with the top of the thumb, drops it, the catcher catches it between finger and thumb
Detail: zero at the thumb / no warning / record the distance at the top of the thumb / convert to time
Repeat (at least 3 times) and calculate a mean
Test without coffee and after drinking coffee (or different volumes) and compare
Same volume / concentration / type of coffee
Same time between drinking and testing
Other controls: same hand, same dropper, same gap, same arm position, same time of day
Several people of the same age / sex / with no other caffeine
Self-marked: Level 3, 6 of 6 marks. You ticked 8 of 8 indicative points. This is your own judgement against the mark scheme.
Model answer: 1. Use the ruler-drop test: a partner holds a metre rule with the zero level with the top of the catcher’s thumb, the thumb and finger a set gap apart and the forearm resting on the table.
2. The partner drops the ruler without warning, at random times, and the catcher catches it. Record the reading at the top of the thumb.
3. Do this 5 times and calculate the mean distance; convert it to a reaction time with the conversion table.
4. The catcher drinks a fixed volume of the same coffee (for example 200 cm³).
5. Wait the same time after drinking (for example 20 minutes), then repeat the 5 drops and calculate the new mean.
6. Compare the means with and without coffee.
7. Keep the same hand, the same person dropping, the same gap and the same time of day. Test several students of the same age, who have had no other caffeine that day.
Unseen data: the same skills, new apparatus
01[3 marks]
A student uses a computer program to measure their reaction time. They click the mouse as soon as a square on the screen changes from red to green. They do six tests.
Reaction times
Test
Reaction time in ms
1
302
2
279
3
77
4
283
5
298
6
294
One result is anomalous. Calculate the mean reaction time, leaving out the anomalous result. Give your answer to 3 significant figures.
Leaves out 77 ms: total of the other five = 1456 ms.
÷ 5.
The mean, in ms, to 3 significant figures.
Full marks. That is exactly what the mark scheme is looking for.
Model answer: 77 ms is anomalous (too fast to be a reaction: the student clicked before the square changed).
Mean = 1456 ÷ 5 = 291 ms.
02[2 marks]
Sprinters push against the starting blocks as soon as they hear the gun. Sensors in the blocks measure each sprinter’s reaction time. In major races, a reaction time of less than 0.100 s counts as a false start.
Reaction times to the gun
Sprinter
Reaction time in s
A
0.165
B
0.137
C
0.076
D
0.173
E
0.138
F
0.168
Which TWO statements are correct? Tick (✓) two boxes.
✓ Sprinter C’s time of 0.076 s is too short to be a reaction to the gun: they started before the sound could reach the brain and back to the muscles. (your choice)
✓ Starting is a reaction, not a reflex: the impulse goes through the brain, which decides to respond. (your choice)
Starting is a reflex, so training cannot change a sprinter’s reaction time.
Sprinter C has the fastest nervous system of the six.
The receptors that detect the gun are in the eyes.
Your answer
Sprinter C’s time of 0.076 s is too short to be a reaction to the gun: they started before the sound could reach the brain and back to the muscles.; Starting is a reaction, not a reflex: the impulse goes through the brain, which decides to respond.
2/2
Sprinter C’s time of 0.076 s is too short to be a reaction to the gun: they started before the sound could reach the brain and back to the muscles.
Starting is a reaction, not a reflex: the impulse goes through the brain, which decides to respond.
Full marks. Clear and precise.
Model answer: The receptors in the ears detect the sound; impulses travel along a sensory neurone to the brain and along motor neurones to the leg muscles (effectors). That takes about a tenth of a second or more, so 0.076 s means sprinter C started before the gun was heard. Because the brain decides, it is a reaction, not a reflex, and practice can shorten it.
03[2 marks]
Two students do the ruler-drop test. Student P’s mean catch is 8 cm. Student Q, texting on a phone between drops, has a mean catch of 32 cm. Student Q says: “The ruler fell four as far, so my reaction time was four times as long.”
Part of the conversion table
Distance fallen in cm
Reaction time in s
7
0.120
8
0.128
9
0.136
31
0.252
32
0.256
33
0.260
Use the conversion table to calculate how many times longer student Q’s mean reaction time was than student P’s.
Full marks. That is exactly what the mark scheme is looking for.
Model answer: From the table: 8 cm → 0.128 s and 32 cm → 0.256 s. 0.256 ÷ 0.128 = 2.00: only 2.0 times as long, not 4. The ruler speeds up as it falls, so distance is not proportional to time.