Let’s Investigate
An object that is streamlined will move faster
through water than an object that is not streamlined
Great white shark ‘Jaws’
http://www.webweaver.nu/clipart
© Sheila Porter – www.scifest.ie
Testing a Hypothesis
Hypothesis: An object that is streamlined will move faster through
water than an object that is not streamlined.
Materials: Blu-Tack, tall measuring cylinder & stopwatch
1. Discuss the hypothesis with the other members of your team.
2. Identify the variables (see slides 6 and 7).
3. Draw up an experimental plan.
4. Design a chart on which to record the data you collect.
5. Carry out investigation (Remember you may have to modify your
original plan.)
6. Write an account of the investigation into your copybook,
explaining your method and describing your results and
conclusions.
© Sheila Porter – www.scifest.ie
Complete the Chart
Independent Variable
Dependent Variable
Fixed Variables/
Constants
Replicates - Number of
times each shape was
tested
© Sheila Porter – www.scifest.ie
Complete the Chart
Independent Variable
Shape
Dependent Variable
Time taken to travel
distance/speed
Fixed Variables/
Constants
1. Mass of object
2. Distance/Height of water
3. Height of drop
Replicates - Number of
times each shape was
tested
Three
© Sheila Porter – www.scifest.ie
Sample Table of Results
Shape
1
2
3
Trial 1
Trial 2
Trial 3
Average
Time (s) Time (s) Time (s) Time (s)
Distance
cm
Speed
cm/s



© Sheila Porter – www.scifest.ie
Discussion
What problems did you come across in your experiment ?
How did you overcome these problems ?
The scientific method is limited in a number of ways, e.g.
by the extent of our basic knowledge and changes in the
natural world. Can you think of any other factors that
might affect the validity of your results.
In all practical work safety must be a major concern.
Give examples of two safety precautions you observed
when carrying out this investigation.
© Sheila Porter – www.scifest.ie
Animals that move through water
© Sheila Porter – www.scifest.ie
Extended Discussion
1. Some fish have fusiform (streamlined) bodies, e.g.,
salmon while others are laterally compressed
(flattened from side to side), e.g., sole. The shape of
the fish’s body tells us a lot about its lifestyle.
Comment on this statement.
2. In what way might the results be useful if you were
designing swimwear?
© Sheila Porter – www.scifest.ie