Science 7
Review From Last Class…
 Did you…?
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Finish your Simpson Science Assignment?
Put your name on it?
Put it in the pass in bin?
Scientific Method- Senses Lab
Procedure
 In pairs
 One drops ruler, one reacts
 Repeat each sense 5 times (5 trials), for
each of the 3 senses (Sight, Touch,
Sound)
 Record data as you go, switch once you
are finished
6
Biggles’ guide to…
‘Catch the ruler!’
5
ruler
1
Brain
Associative centres
RULER + FALLING =
What should I do
?
4
2
visual information
about falling ruler
8
grasping
action
Eye 3
Visual centres
7
Motor command
to catch ruler
distance
travelled
Arm
Calculating Average
 For each trial you are required to calculate average
or mean of your trials
 Mean= T1+T2+T3+T4+T5
5
 If you had a “dropped” ruler you add it as 30cm
Extension: Calculate reaction time in milliseconds

t=
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2d
g
X 1000
Where:
t = Reaction time (milliseconds)
d = Distance ruler dropped (cm)
g = Acceleration due to gravity (980 cm/sec2)
X 1000
= To convert the time from seconds to milliseconds.
Graphing and Reporting
Bar Graph
30
Sight
Touch
Sound
cm Drop Average
25
20
15
10
5
0
Sight
Touch
Sound
How did you do?
DISTANCE – REACTION
Catch
Distance
(cm)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
TIME CONVERSION TABLE
Reaction time
(milliseconds)
50
60
70
80
90
100
120
130
140
140
150
160
160
170
170
Catch
Distance
(cm)
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Reaction time
(milliseconds)
180
190
190
200
200
210
210
220
220
230
230
230
240
240
250
Ratings
REACTION TIME RATING
Reaction time
(milliseconds)
0-50
50-130
131-175
176-200
201-240
241-250
251+
Rating
Comment
Ultra-fast
Superb
Excellent
Good
Average
Fair
Slow
A clairvoyant catcher… are you cheating?!
Impressive, do you play computer games?
Well done, are you a text messager?
Keep trying, you're not top gun yet!
Not bad – but you’re just Joe Average.
You’d get faster if it were money instead of a ruler!
…ouch! Did the ruler hit your foot? Keep trying!
Remember… Milliseconds are one thousandth of a second. This means that:
One second (s) = 1000 milliseconds (ms)
Half of a second (0.5s) = 500 ms
A quarter of a second (0.25s) = 250 ms
One tenth of a second (0.1s) = 100 ms
Precise versus Accurate
 Accuracy: how close a measured value
is to the actual (true) value.
 Precision: how close the measured
values are to each other.
 So, if you are playing soccer and you always hit
the left goal post instead of scoring, then you
are not accurate, but you are precise!
Think about it…
 After you’ve tested yourself, why not experiment
further. Here’s a few suggestions, do reaction
times vary:
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for people of different ages (children versus adults)?
if you use your dominant hand versus non-dominant
hand?
if you are tired or alert?
for men or women?
depending on your mood?
after an alcoholic drink?
Some Thoughts…
 generally the older you are the longer your
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reaction time (that ruler keeps hitting my foot!)
as you might expect, the dominant hand has a
faster reaction time.
in ‘Catch the ruler’, it helps to pay attention – so
being alert is a great asset.
who is faster ‘men or women’? …you tell me?
mood affects attention and therefore reaction
times.
alcohol greatly increases reaction times.
Formal Lab Report
 You must include the following in your typed
report:
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Problem Statement (written on Wednesday)
Hypothesis (written on Wednesday- do NOT make
changes even if it’s wrong)
Materials used
Data (chart of your trial results; Bar Graph- title, x &
y axis labelled, correct independent and dependent
variables labelled)
Analysis questions (from worksheet)
Conclusion statement (next slide)
Conclusion StatementRERUN
 Restate: Restate the lab experiment. Describe the
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
assignment. (include your independent, dependent and
controlled variables)
Explain: Explain the purpose of the lab. What were you
trying to figure out or discover? Talk briefly about the
procedure you followed to complete the lab.
Results: Explain your results. Confirm whether or not
your hypothesis was supported by the results. (Use
simple language such as, “The results supported the
hypothesis,” or “The results did not support the
hypothesis.”)
Uncertainties: Account for uncertainties and errors.
Explain, for example, if there were other circumstances
beyond your control that impacted the experiment
(“Controlled Variables” that weren’t controlled)
New: Discuss new questions or discoveries that emerged
from the experiment.