Richland Science Lesson
Grade: 4th
Experiment: What are Waves?
Question: What are waves?
Standards
4-PS4-1 Develop a model of waves to describe patterns in terms of amplitude and
wavelength and that waves can cause objects to move.
4-PS4-2 Develop a model to describe that light reflecting from objects and
entering the eye allows objects to be seen.
Duration: 50 minutes
Lesson Components
Estimated Time
Brief Description
Engage/Explain
10 minutes
Explore
5 minutes
Engage/Explore
10 minutes
Engage
5 minutes
What is a wave? Have a
brief discussion and
discuss the different
categories of waves.
Using a slinky, students
will create transverse
and compressional
waves.
Students learn the
different terminology of
waves and build one out
of pipe cleaners
Discuss light and its
properties.
15 minutes
Explore
Using a flashlight and a
variety of objects,
students find out what
happens when light and
matter collide.
Advanced Preparation:
Gather materials a few days before hand.
Materials Needed:
 Mini slinky (can sometimes be found in Target’s $1 bins)(1 per 2
students)
 Pipe cleaners (4 per pair)
Per Group of 3-4:
 Flashlight
 Colored cellophane
 Sunglasses or glass prism
 Mirror
 Water in plastic bin
Procedure: Suggested dialog in bold
Engage (10 minutes)
What is a wave? Ask students to give their definitions of a wave.
A wave is a disturbance that travels through space and time. Waves
transfer energy, but do not transfer matter.
There are 3 types of wave movement: transverse waves,
compressional or longitudinal waves, and surface waves. Transverse
waves have a disturbance that is perpendicular to the direction of
wave motion. If you were to hold a jump rope on one end and have a
friend shake the other end back and forth, the resulting waves would
be transverse. Transverse waves travel through solid matter.
Put up a picture of a transverse wave (at bottom of lesson)
Compressional (or Longitudinal) waves have a disturbance that is
parallel to the direction of wave motion. If you were to stretch out a
slinky and then rapidly move one end in and out, you would see the
coils of the slinky compress and expand. Sound waves moving
through air are a good example of a compressional wave.
Longitudinal, or compressional, waves can travel through liquids and
gasses.
Put up a picture of a compressional or longitudinal wave (at the bottom
of the lesson)
The last type of wave is a surface wave where movement is in a
circular motion, like when an object is dropped in water or waves in
the oceans.
Put up a picture of a surface wave (at the end of the lesson).
Explore (5 minutes)
Let’s see if we can make transverse and compressional or longitudinal
waves with a slinky. Try to make a transverse wave first. Who
remembers what a transverse wave look like?
Hand out one slinky per pair of students. Give students a minute to try
and produce a transverse wave with a slinky.
Please stop and hold all Slinkys still. This is how to make a
transverse wave.
Have a student help you by holding one end while you move your end
of the slinky up and down to produce the waves.
Now you try. Give students 1 minute to make them. Walk around and
help students who are having problems.
Stop and hold your Slinkys still. Now we are going to try and make a
compressional or longitudinal wave. Who remembers what this type
of wave looks like? Give students a minute to try and produce one
with the slinky.
Please stop and hold all Slinkys still. This is how to make a
compressional wave. Have a student help you by holding one end
while you stretch out the slinky and make waves by pushing the slinky
towards the student.
Now you try. Give students 1 minute to make them. Walk around and
help students who are having problems.
Stop and hold your slinky still. Great. Do you think you can make a
transverse and compressional wave at the same time? Please try.
Walk around and help students who may have problems.
Nice job. Put the slinky in the middle of the table and look at me.
Explain/Explore (10 minutes)
In a minute, we are going to make waves out of pipe cleaners. With
your partner, you will bend 4 pipe cleaners to make a wave. Show
students how to bend and connect their pipe cleaners.
Crest
wavelength
cycle
trough
While students are working, draw above diagram on board and label.
Once students are done making their waves, have them point to the
crest. The Crest is the high point of a wave. In this picture, it is the top
of the ‘hump’.
Now point to the trough – The Trough is the low point of a wave. In
this picture it is the ‘valley’.
The Wavelength is the distance between two adjacent crests. Point to
two adjacent crests to show a wavelength.
A wave cycle is the section of the wave from crest to trough and back
ONE TIME. Show this to your partner.
Engage (5 minutes)
Please put your waves down and let’s talk about light.
How Does Light Move? Ask a few students.
Light traveling through free space travels in straight lines but often
behaves as a wave.
Light is incredibly fast – in fact, there is nothing that can go faster. The
speed of light is 299,792,458 meters (or about 186,000 miles) per
SECOND!
How quickly could you circle the earth if you were traveling at the
speed of light? Tell your partner what you think.
That is fast enough to go around the entire earth eight times in a
second!
Explore (15 minutes)
On your tray you have:
a) Flashlight
b) Colored cellophane
c) glass prism
d) Mirror
and I will come around with some water in a plastic container.
You have 4 minutes to explore your with the objects. I will turn the
lights off for 2 minutes and then you will explore with the lights on.
Now use the flashlight to shine light on each of the objects, and also
shine the light through your hand.
While you are doing this, observe and describe what the light does as
it encounters each object. We will first turn the lights off and shine
the flash light on each object and then we will turn the lights back on
and shine the flashlight on each object.
When a light wave encounters an object, they are either transmitted,
reflected, absorbed, refracted, polarized, diffracted, or scattered
depending on the object and the wavelength of the light.
Reflection is when light hits an object and bounces off. Can someone
let me know what object caused the light to reflect? The Mirror. Get
your mirror and flashlight and see if you can make the light reflect.
Refraction is when light waves change direction as they pass from one
medium to another. Can someone let me know what object caused
refraction? The Prism. Use your flashlight and shine it on the prism.
What do you notice?
Hand out a straw to each group. Place your straw in the water. Take a
look at the water line. What do you notice about the straw? This is
also an example of refraction.
Absorption is the process in which energy of light radiation is
transferred to a medium through which it is passing. When the
colored cellophane covers the flashlight, the light appears colored
because the cellophane absorbs all the wavelengths of white light.
Shine the flashlight through the cellophane and tell your partner what
you see.
Afterwards, call on a few students to share their experiences with
each object. Example questions: What happened when you shined
the flashlight on the prism? On the water? On the cellophane? Was
there a difference if the class lights were off vs. on?
Terminology:
A wave is the transport of energy without the transport of matter.
Waves can travel through mediums such as sound, light, or water.
Absorption is the process in which energy of light radiation is
transferred to a medium through which it is passing.
Reflection is when light hits an object and bounces off.
Refraction is when light waves change direction as they pass from one
medium to another.