Key Learning Area
Just a little flat!
Science
English
Mathematics
Year levels
Activity overview
Years 3–4
This activity is used to explore energy and forces and the effect of having a football
contain varying amounts of air. An experiment about air amounts is planned and
undertaken, then used to gather data to back up claims. The students will create
a graph of the data to help identify and explain trends or patterns.
Students apply their understandings to a new situation, viewing various video/CD-ROM
segments of AFL matches and predicting what might occur if a fully inflated ball was
replaced with a semi-inflated ball. The students will develop an explanation text.
Time required
Materials
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Worksheet 1: Our investigation
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Worksheet 2: What’s happening?
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Two balloons
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Pan balance
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Inflatable AFL footballs, hand pumps and inflating needles
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Large sheet of paper (backdrop to measure bounce height)
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Measuring equipment/metre ruler (one per group)
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AFL CD-ROM and computer
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Primary Connections Science Program, supported nationally by the
Commonwealth Department of Education Science and Training (DEST).
This model uses the ‘five Es’ (engage, explore, explain, elaborate and evaluate)
and will be useful for teachers.
Preparation
Pump up a football to determine the suitable number of pumps required for each
of the footballs to be tested. For example:
•
Zero pumps – flat
•
20 pumps – quite flat
•
40 pumps – half inflated
•
60 pumps – three-quarters inflated
•
80 pumps – fully inflated
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Approximately 180 minutes
Label each of the balls clearly to indicate the number of pumps.
© 2008 Australian Football League
This will vary depending on the size of football and the size of the pump used. Note
that pumping should be done the same way each time, ensuring the pump handle
is extended to the maximum and fully depressed. Pump up to only recommended
inflation. If the ball feels hard it will be sufficiently inflated. The Physical Education
teacher may have a gauge to measure the air pressure in PSI to ensure the balls
are not over-inflated.
Arrange computer access and view the Bounce Ball Bounce video clip on the AFL
CD-ROM. The video clips are available in the Resources section of the AFL CD-ROM.
A fully-inflated football dropped from a height onto a hard surface bounces well
because the ball stores energy. The air, compressed during the bounce, returns
the energy quite efficiently during the rebound. An under-inflated football, however,
doesn’t bounce as well. The under-inflated football absorbs much of the energy
bending its leather surface during the bounce. The leather doesn’t return energy very
efficiently during the rebound. When you kick a ball, rather than dropping it on a hard
surface, a similar result occurs. Whether a moving ball hits a stationary surface or a
moving surface, the ball is still bouncing from a surface. When you kick a football with
your foot, the football is bouncing from your foot. A fully-inflated football will bounce
more efficiently from your foot than an under-inflated ball. The fully-inflated football
will rebound at a higher speed and therefore travel further.
Activity steps
Activity 1: Footballs contain air
Provide the following four items and ask students to identify the odd one out:
an air mattress, a cricket ball, a football and a bicycle tube.
What do three items have in common that the remaining one does not? Accept all
answers which students are able to justify, as there is more than one answer. One
suggestion may be the cricket ball is the odd one out because the air mattress,
bicycle tube and football all contain air.
Discuss students’ explanations about why air is used inside each item.
Activity 2: What do we know about air?
Use a balloon to describe some of the properties of air.
•
Air is an invisible gas that takes up the shape of its container. Inflate the balloon,
demonstrating how the air pushes out against the inside surface area of the
balloon (air pressure). Explain that the outside air is also pushing in on the
outside surface of the balloon.
© 2008 Australian Football League
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Background information
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Air has mass. Ask students if air has mass. Use a pan balance to compare
two uninflated balloons. Balance the two balloons, then inflate one and place
it back on the pan balance. The inflated balloon should cause that end of the
pan balance to lower, indicating that it is heavier than the uninflated balloon.
•
Demonstrate the elastic properties of the inflated balloon. Show that, when
squashed (ie subjected to a pushing force), the balloon changes shape, then
returns to its original inflated shape. Demonstrate the same effect on an
inflated football.
Activity 3: Explore energy and forces
Explore energy and forces by kicking an inflated and semi-inflated football. In a team
of three, students kick a football. They compare the distance the football travels when
providing a small kicking force and a large kicking force. They consider the energy
given to the ball.
They can sketch and jot down ideas out on the field. Ask students what forces
are involved when they kick the ball, when it is travelling, and when it finally stops.
Provide students with semi-inflated footballs to compare.
Activity 4: Explanation
After returning to the classroom, students discuss their ideas and each develop
a multi-modal explanation about the forces and energy involved in kicking an inflated
and semi-inflated football. The multi-modal explanation is a combination of text,
images and symbols such as arrows.
Students describe what they know about energy and forces, referring to their multimodel explanations. Discuss the role of gravity in the football’s travel, the effect of
magnitude (size) of force, and how air resistance acts against the football to slow
the ball. Ask students:
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How would you describe the energy of a stationary/moving football?
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What is the role of air in the football?
Activity 5: Planning and conducting an investigation
Review students’ ideas about forces and perceived differences when kicking an
under-inflated and fully-inflated football. They will most likely make the claim that
a ball that is not pumped up will not travel as far as a ball that is fully inflated. Discuss
the need, as young scientists, to back claims up with evidence. Plan an investigation
to gather data that will support their claims.
© 2008 Australian Football League
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Students observe the path of the ball from side-on to the kicker.
•
change one thing (the amount of air in the ball)
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keep everything else the same (the release height, the landing surface, how the
ball is released, and the method of pumping the ball)
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measure the effect (the height the ball bounces).
Discuss using a reference point such as a backdrop (a large sheet of white paper
with grid or markings) to assist accurate measurements. Students record their
results on Worksheet 1: Our Investigation.
Discuss safety issues that may arise when releasing the ball. Suggest an
appropriate site to release the ball (eg a platform, a stage with a rail). At no point
allow students to stand on top of a chair balanced on a table. Ensure students
do not over-inflate footballs.
Reducing complexity: The investigation can be modified to suit your students’
level of experience in planning and conducting investigations. Modifications
might include the following:
•
Modelling the investigation in front of the class using students to carry out certain
parts of the investigation, providing guidance with the measurement practices,
recording of data and development of a graph.
•
Reducing the data being collected. For example, take three measurements, that
is, of a flat, semi-inflated and a fully inflated football and/or use an adult helper
to assist students to pump the ball correctly. Rather than using centimetres as
standard units, mark actual heights on the backdrop and use informal units or
actual strips of paper to compare bounce heights.
•
Presenting the data. Review or discuss the presentation of data using a suitable
graph. Review or discuss axis X and axis Y.
Height (cm) a football, pumped with different amounts of air,
bounces when released from a height of 2m
bounce height in cm
120
100
80
60
40
20
0
zero pumps- flat
20 pumpsquite flat
40 pumps- half
inflated
60 pumps-3/4 80 pumps- fully
inflated
inflated
number of pumps
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Pose the question: Does the amount of air in the football affect the height the football
bounces? Explain that in their investigation they will:
Example of a graph Football Bounce height
© 2008 Australian Football League
Activity 6: Bounce Ball Bounce video
View the Bounce Ball Bounce video clip in the Resources section of the AFL
CD-ROM. Ask students to choose one section of this segment which is of interest
to the experimental activity.
Pause the section as the action is about to unfold and ask students to imagine what
would happen next if the match football was semi-inflated.
Explain that their task is to develop three images (a storyboard) with captions
to describe the action.
Students use Worksheet 2: What’s happening?
Students may need to view the video segments several times to select a suitable
section. Provide an opportunity to view students’ storyboards and explanations.
•
Use students’ individual drawings of the forces involved in kicking an inflated
and semi-inflated football to help assess their understanding of forces.
The scientific drawing may include such things as:
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the size of the force from the kick (which provides the ball with
moving energy)
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gravity (as the force that pulls the ball back to the ground)
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air resistance (which slows the ball and reduces the distance the ball travels)
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the path the football travels (represented as an arc)
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the ball bouncing (and thus losing the remaining energy).
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Students’ worksheet containing their table of results and graph of their
investigation.
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Students’ storyboard and explanation text showing the effect of having
a semi-inflated football.
Optional extension
Students could plan a further investigation to test other variations. For example:
•
Does the landing surface affect the height the football bounces?
•
Does the point at which the ball hits the ground affect the height the
ball bounces?
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Does the release height affect the height the ball bounces?
© 2008 Australian Football League
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Assessment ideas
Worksheet 1: Our investigation
Name: ______________________________________________________________________
Our group is testing … ______________________________________
____________________________________________________________
____________________________________________________________
We are keeping everything else the same ____________________
_____________________________________________________________
We will measure ____________________________________________
Safety considerations in our investigation are ________________
____________________________________________________________
____________________________________________________________
Our results
Amount of air in football
Bounce height
Zero pumps (flat)
How accurate do you think your results are?
© 2008 Australian Football League
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We are changing one thing __________________________________
Worksheet 1: Our investigation (Continued)
Our group found out:
We think that when you kick a football that is not fully pumped …
We know this because …
© 2008 Australian Football League
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Use this grid to graph your results:
Worksheet 2: What’s happening?
Name: ______________________________________________________________________
Draw your storyboard to show your prediction if the match football was replaced with
a semi-inflated football.
Add your explanation below each drawing to support your ideas.
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(production note: provide
filmstrip type border to
bolded boxes)
© 2008 Australian Football League