Investigation: Reaction Time Ruler Test
Date:
Name:
Partners Name(s):
Marks:
/22 (Group)
+
/18 (Individual)
=
/40
INTRODUCTION:
Reaction time is the time between the application of a stimulus and the body’s response to the
stimulus. Reaction time is quickest for young adults and gradually slows down with age.
Reaction time can be improved with practice, up to a point, and it declines under conditions of
fatigue and distractions.
INSTRUCTIONS:
PART 1 (Group):
 The practical procedure and written work will be done in one lesson.
 You will do this practical in pairs unless your teacher asks you to make a group of 3 in
which case there are additional spaces added below for your data.
PART 2 (Individual):
 All the questions at the end of this investigation will be done individually.
 You may use calculators for all working out.
Extension work: For a more in depth investigation you can collect data from the entire
class and work out exact reaction times using a formula shown on page3.
PART 1 AIM: To measure and compare the different average reaction times of learners in a Life
Science class when a standard 30cm ruler is dropped and caught.
MATERIALS:
30 cm rulers (one ruler per group)
Calculator
1
METHOD:
1. Have your partner hold the ruler from the top. (As shown in fig 1. below)
2. Line up your fingers at the bottom end of the ruler. Do not touch the ruler!
3. Prepare to catch the ruler by bringing your fingers and thumb together when it drops.
4. Have your partner drop the ruler without warning. Don’t chase after the ruler as it falls.
5. Read your reaction time off the conversion Table 1 on page 3.
6. Record the reaction time that is closest to the distances given in the table to which you
caught (i.e. if you caught the ruler at 6cm your reaction time will be 100ms as you are
closest to 5cm as recorded in the table).
7. If ruler is missed completely record the miss with a dash and adjust average based on
the number of catches only.
8. Each partner must have 10 attempts at grabbing the ruler.
9. Three trials (practice attempts) each may be done before you begin recording your
results.
10. Record the results in Table 2 on page 3.
11. Work out the average reaction times.
Extension work: Record entire classes individual reaction times.
For those who want more precise reaction times, the formula on page 3 can be used.
Fig. 1 Photograph illustrating the starting point of the reaction time ruler test (left) and how the ruler must be
caught once dropped (right).
2
Table 1. A table showing the conversion between the distance the ruler falls (cm) and the
reaction time (ms) in trying to catch the ruler.
Distance Ruler Dropped (cm)
Reaction Time (ms)
±5
(0.1-7.4)
100
± 10
(7.5-12.4)
140
± 15
(12.5 -17.4)
170
± 20
(17.5-22.4)
200
± 25
(22.5- 27.4)
226
± 30
(27.5- 30)
247
OR to be more accurate calculate reaction time using the formula shown below
Extension work: Formula for working out reaction time in milliseconds:
t=
Where:
t
=
d
=
g
=
X 1000 =
2d
g
X 1000
Reaction time (milliseconds)
Distance ruler dropped (cm)
Acceleration due to gravity (980 cm/sec2)
To convert the time from seconds to milliseconds.
3
PART 1: GROUP WORK FOR INVESTIGATION
1.
Fill in and complete the table below:
Table 2. A table showing the distance the ruler dropped after being caught (cm) and then this
distance converted into a reaction time (ms) using the conversion found in Table 1 or the
formula.
Attempt
Partner 1
Distance
dropped
(cm)
Reaction
Time (ms)
Partner 2
Distance
dropped
(cm)
1
2
3
4
5
6
7
8
9
10
Total
4
Reaction
Time (ms)
Partner 3 (if applicable)
Distance
dropped (cm)
Reaction
Time (ms)
2.
Use the information in the table above to calculate the average reaction time for each
partner.
PARTNER A:_______________________________________________
PARTNER B:___________________________________________________
PARTNER C (If applicable):___________________________________
5
3.
Draw a table summarising the average reaction times (calculated on page 5) of the
learners in your group in the space below.
6
A hypothesis must be a statement (that usually follows on from the aim), is testable and
shows a relationship between the independent and dependent variables. Your teacher
will tell you which option to complete below in formulating a hypothesis.
OPTION 1 (Grade 12):
4.1
Write out a hypothesis for this investigation:
(3)
OPTION 2 (Other grades):
4.1
Select one of the hypotheses listed below and circle it. All further questions/answers
need to relate to your chosen hypothesis:
a)
Student X (insert name of partner here) will have a faster average reaction time
than student Y (insert name of partner here) when a 30cm ruler is dropped and
caught.
b)
Student X (insert name of partner here) will have the quickest single reaction
time when a 30cm ruler is dropped and caught.
c)
Student X (insert name of partner here) will have the slowest single reaction
time when a 30cm ruler is dropped and caught.
d)
Student X (insert name of partner here) will have the fastest average reaction
time in the whole class when a 30cm ruler is dropped and caught.
e)
All students will have the same average reaction times when a 30cm ruler is
dropped and caught.
(3)
5.
Identify the independent and dependent variable in this investigation. These variables
should directly link to your hypothesis.
Independent:________________________________________________________
(Hint: The independent variable is the variable you are changing or manipulating)
(1)
Dependent: __________________________________________________________
(Hint: The dependent variable is the variable you are measuring or observing)
(1)
7
6.
State at least THREE variables that you kept the same for this investigation (fixed
variables). (Fixed variables are all the other variables besides the independent and
dependent that you need to keep the same to increase the validity of the investigation.
These should be written as sentences which describe how the variables are fixed).
(3)
Group Assessment
Criteria
1. Table 2 filled in with all data and complete for all partners.
2. Calculations of average times correct and worked out for all
partners.
3. Table completed summarising the average reaction times
of the partners in a group. Table has appropriate heading,
drawn with a ruler, rows and columns are correctly drawn,
units are placed in the headings and contents correctly
added in.
4. Hypothesis is correctly stated, is testable and shows a
relationship between the independent and dependent
variable (4.1 OPTION 1).
OR
One hypothesis is selected and circled and all further work
relates back to the hypothesis that was selected (4.2
OPTION 2)
5. Independent and dependent variable correctly identified.
6. Minimum of three fixed variables are identified and
correctly stated.
TOTAL
8
Mark obtained
2x2
=
/4
/4
/6
/3
/2
/3
/22
PART 2: INDIVIDUAL WORK FOR INVESTIGATION
1.
Name:
In the space below, draw a bar graph to compare the reaction times in your
investigation.
Rubric for Graph:
Criteria
Detailed title of graph which includes independent and
dependent variables is given above the graph.
X axis is correctly labelled and the scale is correct.
Y axis is correctly labelled, units are given and the scale is
correct.
Axes are drawn with a ruler in pen and headings and labels are
written in pen and graph is drawn in pencil using a ruler
Bars are not touching, of equal size and plotted correctly
TOTAL
9
Mark obtained
/1
/1
/1
/1
/2
/6
2.
Based on your results, which partner had the slower reaction time.
(1)
3.
Write out a conclusion for this investigation. (Your conclusion must relate directly to
your hypothesis and to your results which should either support or not support the
hypothesis.)
(3)
4.
Identify the stimulus and the response in this practical.
Stimulus:__________________________________________________________
(1)
Response:_________________________________________________________
(1)
5.
The average reaction times for six other Natural Science classes are shown below:
Class
1
2
3
4
5
6
Reaction
Times
(ms)
120
110
140
240
160
130
10
5.1
What are the units for measuring reaction time?
(1)
5.2
Rank the sets from quickest to slowest, listing them from left to right, in terms of their
reaction time (left being the quickest to right the being slowest).
(1)
5.3
One of the sets had a Maths test the same day they were doing their natural science
practical on reaction times. Many of the pupils in this set were up all night learning for
this test. Which set do you think this was?
(1)
5.4
Explain, giving a reason, why you chose this particular set?
(3)
/18
11