Topic: Waves
Level: Secondary 3 Express
Class Size: 40
Lesson objectives: At the end of the lesson, the students should be able to
(a) explain that waves transfer energy without transferring matter
(b) identify wave motion as the vibration of particles in the medium
(c) compare transverse and longitudinal waves (in terms of wave motion) and give
suitable examples of transverse waves
(d) define speed, frequency, wavelength and amplitude
(e) interpret the relationship velocity = frequency x wavelength
Prior knowledge
(a) Lower Secondary General Science concepts
Concept Map
Waves
Properties
Period
(T)
Frequency
(f)
Wavelength
()
types
Amplitude
transverse
longitudinal
Wave motion
Speed (v)
Due to vibration of
particles in medium
f = 1/T
v = f x 
Vibration of
particles
perpendicular
to direction of
wave
propagation
Vibration of
particles
parallel to
direction of
wave
propagation
Learning Aids and Resources

Set induction: Video

Demonstrations: ripple tank, slinky, students to do 'kallang wave'

Powerpoint (All the powerpoint slides are placed in Appendix 1)

IT Websites: (i) Applets to
1) describe the properties of waves (A1)
2) compare longitudinal and transverse waves and show
that wave motion is due to vibrations of the particles in
the medium (A2)
3) illustrate the wave equation to ripples in water (A3)
Links to applets provided in Summary of Lesson Plan

Worksheet on Stadium wave (Appendix 2)
Trigger Activity




Show a short snippet of the movie 'Deep Impact' where the comet hits the ocean.
There is an obvious ripple that is formed in the ocean on impact
Ask the students how the energy of the impact can reach people on land
Tell them that the energy of the impact is transferred to land through waves that
were generated when the comet hits the ocean
Tell the students that this is the important aspect of waves we use in everyday life
– to transfer energy. Let them know that we will be learning about the general
properties of waves
Lesson Development
1) Everyday applications and the transfer of energy (not matter) by waves
The trigger activity will set the students to think about the usefulness of waves in
transferring energy, and other examples of waves they encounter in everyday life
where there is bound to be the transfer of energy involved. It will then be
emphasized that in all the examples they have mentioned, waves only transfer
energy and not matter
2) Student participation
Student volunteers will demonstrate waves of differing frequency and wavelength
using slinkys. They will also be asked to help demonstrate the application of the
wave equation (the inter-relation of frequency, wavelength and speed of wave)
on a longitudinal wave using the slinky.
Students will also be asked to demonstrate the 'kallang wave' to trigger the lesson
segment on wave equation for waves. This involves everyone in class and relates
the concept to something they are familiar with.
3) Use of IT
Applets and powerpoint slides are used to explain the properties of waves
(amplitude, wavelength, frequency and period) as well as the different types of
waves (longitudinal and transverse).
An applet showing the ripple tank demonstration is used to make it clearer to the
students that ripples in the water are actually transverse waves. The applet is also
used to further demonstrate the wave equation
4) Teaching Aids and Materials
Slinkys, the ripple tank and the kallang wave will be used to demonstrate that
waves transfer energy, not matter. These are also used to demonstrate the motion
of particles in a medium for transverse waves. For instance, in the ripple tank
demonstration, a small floating cork is placed on the water. When the waves is
generated, the cork will only bob up and down but will not move across the
surface of the water. The students are then asked to think of a way to demonstrate
the same concept using a slinky and carry out the demonstration.
When the students are asked to do the kallang wave, they are asked whether the
wave is a transverse or longitudinal wave and ask them to explain why.
A short worked example on wave equation applied to stadium waves will be done
together with the students at the end of the lesson to practise what they have learnt
and link the concept of the wave equation to the stadium wave which they have
demonstrated earlier.
Lesson Closure
A summary of the lesson will be given using powerpoint slides. The students will
be given a brief insight of what they will be covering in the next lesson to get
them prepared. In the next lesson, they will be practising further on the wave
equation, learning more about longitudinal waves (compressions, rarefactions and
examples of longitudinal waves), and also learn about wavefronts.
Summary of Lesson Plan
The 12 min microlesson will cover the segment of the lesson plan that is in blue
Time Activities
frame
5
Set trigger activity
mins  Show the video snippet of 'Deep Impact'
Resources
Remarks
Video
Relates the
importance of
waves (transfer of
energy) to what
they are familiar
with (movies and
possible real-life
occurrence)
Ripple tank
and slinky
Get the students to
be involved and
think creatively to
put across what
they have learnt.
This activity will
help visual and
kinesthetic learners.
 Explain the importance of waves in the
transfer of energy
 Explain that waves is defined as a
disturbance that moves through a medium,
transporting energy from one location to
another as it goes
20
Demonstrate how waves transfer energy but not
mins  matter
 Demonstrate this concept using the ripple tank
by placing a cork on the water and show that
it bobs up and down only when the waves are
generated
 Provide each group with a slinky. Ask them to
think in groups how they can demonstrate the
same concept using the slinky

15
mins
Ask one group to demonstrate to the class
Introduce the physical characteristics of a wave
 Describe the wavelength, amplitude, frequency
and period of a wave using powerpoint
 Use Applet from the website
http://www.surendranath.org/Applets.html (A1)
waves
transverse waves
to illustrate the frequency of a wave
Powerpoint
5
mins
 Explain using an applet that wave motion is
due to the vibration of the particles in the
medium
powerpoint
http://www.cbu.edu/~jvarrian/applets/waves1/lon
tra_g.htm (A2)
- emphasize the different motion of the particles
in the medium for transverse waves compared to
longitudinal waves
- emphasize that a medium is required in order
for a mechanical wave to be generated (briefly
explain that this is true for mechanical waves, not
electromagnetic waves which will be covered in
the next chapter)
5
mins
2
mins
slinky
 Use slinky to differentiate transverse and
longitudinal waves
 Ask the students to do the kallang wave
- ask them to identify whether it is a
transverse or longitudinal wave and why
- ask them if they know that the speed of a
stadium wave can be calculated if we know the
characteristics of the wave they just learnt.
2
min
 Explain what is speed of wave using an
applet
- let the students visualize what is speed of the
wave by showing only one full wavelength of a
wave moving across the screen. Then explain
that this speed is the same as one specific crest
or one trough of a continuous wave
 Introduce the wave equation v = f x  using
powerpoint slide
- make the students realize that v = f x 
can be derived using the familiar equation of
distance per unit time
Powerpoint
Doing the kallang
wave is an
opportunity for
the students to
relate waves to
something they
are familiar with.
It is also an
activity that
involves everyone
in class.
- emphasize that the speed of the waves is not
the same as the speed of vibration of the
particles in the medium
- emphasize that the wave equation only lets us
calculate the speed of the wave if we know the
frequency and wavelength, it does not imply
that the speed is dependent on wavelength or
frequency. In fact, the speed of the wave is
only dependent on the medium that it is
propagating through. Explain that this is so
because the wave speed is dependent on the
elasticity of a material which is fixed for a
specific medium.
3
min
Application of wave equation on transverse
waves
Powerpoint
 Using the applet from the website
http://www.falstad.com/ripple/ (A3)
show that ripples in a water are actually
transverse waves and demonstrate how the
frequency of the wave can affect the
wavelength if the speed remains the same
5min
Application of wave equation on longitudinal
waves
 Using the slinky and the help of 1 student,
demonstrate longitudinal waves of differing
frequency but same speed.
 Tell the students how to identify one
wavelength (since they are not taught yet
how to identify compressions and
Applying the wave
velocity equation
to water ripples
will ensure that
students can relate
this concept to
something they see
in everyday life
The applet is also
useful because the
3d diagram can be
rotated to a crosssectional view so
that it is clearer to
students that the
ripples actually
form a transverse
wave
Slinky
Using the slinky to
demonstrate that
the wave equation
can also be
applied to
longitudinal
waves. The use of
slinky also help
the visual learners
understand it
rarefactions)
better
 They will note that the wavelength will
increase if frequency is smaller according to
the wave equation, and vice versa.
5
mins
 Work through a worksheet with them to find the Worksheet
(Appendix
speed of a stadium wave moving round a
2)
stadium
3
mins
 Give a summary of what has been learnt in the
lesson using the concept map in the
powerpoint

Let the students know what to expect for the
next lesson
- they will be practicing more on the wave
equation
- they will be learning further on characteristics
of longitudinal waves (compressions &
rarefactions)
- they will be seeing more of the ripple tank as
they will be learning about wavefronts
- Ask the students to of examples for longitudinal
waves to prepare for the next lesson
Powerpoint
Although the
students will not
be able to identify
compressions and
rarefactions
(which will be
covered in the
next lesson), this
activity is just a
demonstration to
show them that
wave equation can
also work for
longitudinal waves
The worksheet
assigned to them
will link back to the
activity they
demonstrated
earlier – the
'kallang wave'
The use of concept
map can help the
students to get the
big picture and the
links between
concepts they have
learnt in the lesson
Providing an
insight on the next
lesson gets the
students prepared
Conclusion
This lesson is suitable for average ability students. Since this is the first time they are
encountering the wave topic, getting them involved and letting them see the effects of
waves in everyday life (for eg 'kallang wave' and water ripples) and how it is used in their
favourite movies (video snippet of 'Deep Impact) can help in their understanding and
arouse their interest. The use of this video for the lesson induction serves to capture the
students' attention and also make them realize the importance of waves as a means to
transfer energy although they cannot 'see' waves.
Waves are abstract so IT and materials are also used to a great extent. Applets are useful
for them to visualize some concepts (for eg motion of a wave due to vibration of particles
in the medium) and the use of slinky for hands-on activities can help the kinesthetic
learners better.
Reflection
In my microlesson, the Kallang Wave demonstrated by the class was purposeful in that it
was meant to arouse the attention of the class, considering that the segment of the lesson
was supposed to be towards the end of the lesson. However, as Dr Chen pointed out,
depending on where the class is situated, doing the kallang wave might not be a good
activity if it is held in the classroom and where classes are situated near to each other.
This is because the activity can be quite noisy and it might disturb neighbouring classes
that are going on. If this is the case, a video of the stadium wave can be shown instead.
Before I explained further how to derive the speed of the wave, I should explain what
speed of wave is because it is difficult for the students to visualize the speed of the wave.
In worked examples 'Worksheet on Stadium Wave' that I illustrated to the students, I
should not use fractional values for concrete things like 'number of waves per second is
1.25' because it might be difficult for the students who are only just exposed to the topic
to visualize what is '1.25 of a wave'. Hence, I changed the question in my final lesson
plan such that the values obtained will be more acceptable to the students.
During the microlesson, I emphasized that the speed of the waves are actually not
dependent on the frequency or wavelength. Instead, it is dependent on the medium that
the wave is propagating through. So the wave equation just tells us how to find the speed
of the waves using the wavelength and frequency of the wave. It does not imply that the
speed of the wave is dependent on wavelength nor frequency. Instead of just emphasizing
this, it would have been better if I explained further why this is the case. I could have
explained that the speed of the waves is dependent upon the medium only because the
wave speed is dependent upon the elasticity and tensile strength of a material. Since a
medium has a definite elasticity, any wave that passes through it will have the same
speed.
References
GCE ORDINARY LEVEL Physics Syllabus (5052)
http://www.surendranath.org/Applets.html
http://www.cbu.edu/~jvarrian/applets/waves1/lontra_g.htm
http://www.falstad.com/ripple/
http://en.wikipedia.org/wiki/Wave
http://www.sciencenews.org/articles/20020914/mathtrek.asp