Lesson Plan 22
Making Waves
In deep water,* every water molecule moves in a circular orbit and returns to its
starting position as a wave passes by. In this activity, students build a simple
computer model of a water molecule’s orbital motion using standard presentation
software.† They copy, paste and animate their model to discover the motion of
individual water molecules hidden within every wave.
Students can share their animations by converting the presentation to a movie
format that can be uploaded to the school website, social networks or YouTube.
This lesson plan should be used in conjunction with the instructional video of how
to build the wave animation in the lesson plans section of the Surfing Scientist
website at: abc.net.au/science/surfingscientist/lessons
* Deep-water waves are waves travelling in water deeper than half the wavelength of the wave. (See
†
introduction to waves on page 3.)
This animation can be created with Microsoft PowerPoint (PC) or Apple Keynote (Mac).
Duration:
Year Level:
Topics:
Preparation:
45–60 minutes
Middle to upper primary, secondary
Energy, motion, water waves, computer skills, multiplication and
division, circles, geometry
5–15 minutes
Overview
Whole class
Introduce and discuss lesson on SMART BOARD.
Individual
Students design, format and test the behaviour of their molecules.
Next, they copy, paste, align and animate to create their wave
model.
Whole class
Optional: students present their wave model on the SMART BOARD
or projector.
Materials
• Requires either Microsoft PowerPoint or Apple Keynote software.
• Student worksheet.
Preparation
Photocopy worksheets and introduction to water waves (4 to 6). Try building the
animated model yourself so that you can foresee problems and assist if students
have difficulties.
Lesson Plan 22 – Making Waves | Page 1
© 2011 | ABC Science Online
Objectives
Science concepts
In ‘deep water’, the water molecules in a wave move in circular
orbits.
The distance between two wave peaks is called the wavelength.
The time it takes two wave peaks to pass a stationary point is called
the wave period.
Waves moving in water deeper than half the wavelength of the
wave are called deep-water waves.
Waves moving in water shallower than one-twentieth of the
wavelength of the wave are called shallow-water waves.
Deep-water waves do not reach or interact with the sea floor.
Shallow-water waves interact with the sea floor.
The molecules in shallow-water waves move in elliptical orbits that
become flat at the sea floor.
Numeracy skills
Calculate the number of increments.
Calculate the angle to set each molecule.
Computer skills
Draw, format and align objects.
Copy, paste and animate drawing objects.
Procedure
Discuss the lesson
Discuss ocean waves and demonstrate your animated wave model on the
SMART BOARD or play the wave animation online video. Discuss how to draw,
format, copy, paste and animate the objects.
Students use computers to create wave animation
Distribute worksheets and assist students.
Optional class presentation
Students copy their presentation to a USB memory device and load onto the
SMART BOARD to present the animation to the whole class.
Lesson Plan 22 – Making Waves | Page 2
© 2011 | ABC Science Online
Teacher Notes
These notes are further to the student worksheet
STEP 1 – Draw a molecule
The basic unit only needs to be drawn once. It consists of two
circles grouped together so the smaller circle (‘molecule’) rotates
around the centre of the larger circle (‘orbit’). An additional circle
in the centre and a vertical line can be added to make the
rotation around the circular orbit clearly visible during the
animation. Any resizing may require reformatting of line
thicknesses, followed by realignment.
STEP 2 – Copy, paste, align and preset angles
Once the basic unit has been drawn, copy and paste so that nine orbits fit side by
side across the slide. The remaining 16 molecules are distributed evenly between
Molecules 1 and 9. (See hint* below.)
The preset angle of 15° between molecules is calculated by dividing a full rotation
(360°) by 24. Note that there are 25 molecules but molecules 1 and 25 start in the
same orientation, hence divide 360° by 24 (not 25). To preset:
PowerPoint: Format Shape > Size > enter angle in ‘Rotation’ setting.
Keynote: Select Inspector > Metrics > entre angle in ‘Rotate’ setting.
Nine aligned side-by-side
25 distributed evenly*
Preset angles
* HINT: distributing the 25 molecules evenly may require drawing 25 vertical lines to use as a guide against which
to align the molecules by hand (using the mouse or the left and right arrows on the keyboard).
STEP 3 – Animate molecules to create wave
PowerPoint: Select ‘Add effect’, then ‘Emphasis Effect’ and choose ‘Spin’. Then set these options: Start
‘With Previous’, Property ‘Two Spins’ (720° Add), Speed ‘Very Slow’. In ‘More Effect Options’ uncheck
‘Smooth Start’ and ‘Smooth End’.
Keynote: Select ‘Inspector’, then ‘Build’ (diamond icon) and choose ‘Action’. Then set these options:
Effect ‘Rotate’, Direction ‘Clockwise’, Rotate ‘720°’, Acceleration ‘None’, Duration ‘5 seconds’ (or more).
Lesson Plan 22 – Making Waves | Page 3
© 2011 | ABC Science Online
Introduction to waves
The waves you see rolling in at the beach are called surface gravity waves. They are generated
by wind blowing over the ocean. The stronger the wind and the longer it blows, the bigger the
waves become. The distance over which the wind that forms waves blows is called the fetch.
After the wind stops, gravity’s pull keeps waves moving until they reach a shoreline and break, or
spread out so much that they are imperceptible. The distance between two wave peaks is called
the wavelength. The time it takes for two peaks to pass a stationary point is called the period.
Waves look like big lumps of water moving across the ocean but this is an illusion. The individual
water molecules move in circular orbits and return to their starting position so that there is almost
no net displacement of water. Waves behave differently in ‘deep’ and ‘shallow’ water. The
diagrams below illustrate what scientists mean by ‘deep’ and ‘shallow’ water when describing the
behaviour of waves.
NOTE: In real waves, the orbits (in red) of both deep and shallow
water waves are not perfectly closed and there is a small
displacement of water called ‘Stokes drift’.
Deep-water waves
When the water is deeper than half the wavelength, the waves are called deep-water waves.
Here, the water molecules move in circular orbits that become smaller with depth. Below a
depth equal to half the wavelength of the wave, the water doesn’t move at all. A scuba diver
below this depth won’t feel the waves above. That’s why they are called ‘surface’ gravity waves
(i.e., they don’t extend all the way to the sea floor). The speed of deep-water waves is around 60
to 100 kilometres per hour and depends only on their wavelength. The longer the wavelength
(i.e., the distance between peaks) the faster the wave.
Shallow-water waves
When a wave enters water that is shallower than one-twentieth of the wavelength (i.e., the
wavelength divided by 20), it becomes a shallow-water wave. The circular motion becomes
flattened into elliptical orbits. At the sea floor, the water molecules can only move back and
forth (not up and down). Friction between them and the sea floor causes the wave to slow
down. In shallow water, a wave’s speed depends only on the depth of the water. The shallower
the water the slower the wave’s speed.
Breaking waves and surfing
At depths between one-half (deep water) and one-twentieth of the wavelength (shallow water),
the waves are called transitional waves. As they move from deep water into shallow water,
waves slow down. If the sea floor is the right shape, they can slow down so rapidly that the top
topples over and breaks towards the shore. This is the point at which surfers can catch and
ride waves.
Lesson Plan 22 – Making Waves | Page 4
© 2011 | ABC Science Online
Wave animation instructions
This animation works with Microsoft PowerPoint (PC) or Apple Keynote (Mac). It models the
circular orbits of water molecules in a deep-water wave.
STEP 1: Draw a water molecule and its orbit
1. DRAW: Draw a small circle to represent a water molecule. Then
draw a larger circle to represent its orbit. Select both circles and
set their horizontal alignment to ‘centre’, and vertical alignment to
‘top’.
Small circle (molecule):
Large circle (orbit):
Fill = solid
Line = none
Fill = none
Line = 50% transparent
OPTIONAL: To make the molecule’s circular motion clearly visible,
add a third, smaller circle aligned to the centre of the orbit and a
thin vertical line.
Centre circle:
Line (orbit):
Fill = 50% transparent
Line = none
Fill = not applicable
Line = 50% transparent
2. GROUP: Select all the drawing objects and group them together.
Animations will now apply to the whole group.
NOTE: the centre of the GROUP should coincide with the centre of the larger
circle so that the GROUP will rotate around this point when animated.
3. RESIZE: In this step, you will scale the group down to fit nine
orbits on the slide with their sides touching.
HINT: The most accurate method to determine the appropriate size is to draw a
horizontal line across the slide, measure its pixel length and divide by nine.
4. CHECK: After resizing check if any line thickness is now too thick.
If so, reformat them now.
NOTE: if you do change any formatting in this step, make sure you realign the
molecule with the top of the orbit. This will ensure the centre of the group is the
same as the centre of the orbit (large circle). If it isn’t, the animation in Step 2
won’t work correctly.
Lesson Plan 22 – Making Waves | Page 5
© 2011 | ABC Science Online
STEP 2: Copy, paste, preset and animate your water molecules
1. ANIMATION: Set the grouped objects to rotate 360° using the
animation features and check that the group rotates about the
centre of the large circle (orbit).
PowerPoint: Set animation to ‘Spin’.
Keynote: Set animation to ‘Rotate’.
NOTE: if the orbit wobbles during the animation, go back to Step 4 and realign
the molecule with the top of the orbit. This ensures the centre of the GROUP is
aligned with the centre of the ORBIT.
2. COPY & PASTE: Copy the group and paste 16 more (the far-left
and far-right molecules should be the same distance apart as in
Step 4. All 25 molecules must be aligned and equally spaced.
HINT: If using Keynote and ‘Distribute horizontally’ causes your molecules to
spread out off the edge of the slide, draw a guide as follows: draw a vertical line
then copy and paste the line so you have a total of 25 lines. Distribute the lines
horizontally so they are evenly spaced and use them as a guide to align the
molecules.
3. PRESET ORBIT ANGLES: Every molecule’s position in a wave is
rotated slightly more than the next. In this model, there are 25
molecules. Molecule 1 is already preset to 0°. Molecule 25 is
rotated by a full 360° (compared to Molecule 1) so it doesn’t need
to be rotated. The remaining 23 molecules in between need to
be preset. Each molecule is rotated by 15° more than the last
(i.e., 360 divided by 24). So, Molecule 2 is set to 15°, Molecule 3
is set to 30°, Molecule 4 to 45° and so on. Calculate the rest, then
select the molecules one by one and do the following:
PowerPoint: Select the molecule then ‘Format Shape’ and click
on ‘Size’. Now type the appropriate angle into the ‘Rotation’ box.
Keynote: Select the molecule then click ‘Metrics’ (the ruler icon in
the ‘Inspector’).
ANIMATE
4. ANIMATE THE WAVE: Select all the molecules so that the
animation features you set applies to each one. Then set the
animation options as follows:
PowerPoint: Select ‘Add effect’, then ‘Emphasis Effect’ and
choose ‘Spin’. Set these options: Start ‘With Previous’, Property
‘Two Spins’ (720°), Speed ‘Very Slow’. In ‘More Effect Options’
uncheck ‘Smooth Start’ and ‘Smooth End’.
Keynote: Select ‘Build’ (diamond icon in ‘Inspector’) and select
‘Action’. Set these options: Effect ‘Rotate’, Direction ‘Clockwise’,
Rotate ‘720°’, Acceleration ‘None’, Duration ‘5 seconds’.
STEP 3: EXPERIMENT
You can make a longer wave by resizing, copying and pasting all the molecules to make a second
wave. Align the copied wave with your first wave and animate. Experiment with the speed of the
wave by changing the timing of the molecule’s rotation.
Lesson Plan 22 – Making Waves | Page 6
© 2011 | ABC Science Online