Nick Webster
Title:
Slinky Waves
Summary:
In this forty-five minute exercise students will explore earthquake waves and
show the students the different ways energy propagates through matter. The exercise will
consist of groups of two using the slinkys to create waves. Then using our slinky models
we will show how it propagates though different soil.
Grade Level:
3-6
Subject(s):
How earthquakes propagate through soil
How energy is transferred
What about an earthquake causes damage.
How earthquakes occur
Duration:
Forty-Five Minutes
Materials:
Enough slinkys for every two students.
A large flat smooth space for them to perform the experiment.
A length of rope equal to a stretched slinky length for every two students.
Our large to small slinky example (Fig 1).
Vocabulary:
Fault: A place where one piece of the earth's crust is moving against another. It can be
vertical or horizontal.
Footwall: (Fig.2) When a fault is vertical and sloped, it is the part of the fault that is
sloped downward. NOTE- it is shaped like a foot.
Hanging wall: (Fig. 2) When a fault is vertical and sloped, it is the part of the fault that
has an overhang.
Normal Faults: (Fig.3) Faults in which the force on the fault is a pull, and so the
footwall and hanging wall are being separated. This makes the hanging wall slide down
the footwalls face.
Reverse Faults: (Fig.3) Faults in which the force on the fault is push, and so the footwall
and the hanging wall are being forced together. This makes the hanging wall slide up the
face of the footwall.
Strike-slip Faults: (Fig. 3) Faults in which the fault itself is horizontal not vertical.
Therefore there is no push together or pull apart of the curst pieces, but a friction filled
scraping of their sides as they pass by each other. NOTE- the San Andreas Fault is this
type.
S-Waves:(Fig. 4) S-waves, or secondary waves, are the second fastest waves from an
earthquake and are the ones that cause the most damage. S-waves move perpendicular to
the direction of the cause, in a wave similar to ocean waves.
P-Waves:(Fig. 4) P-waves, or primary waves, are the fastest traveling body waves
which propagate out from an earthquake. It moves in a longitudinal way, using
compression to transfer it self through the medium.
Procedure:
0-5 minutes
Have the children scoot all the desks to the sides or find another large flat space
for them to perform the slinky experiment. Have them sit in two parallel rows that
eventually the slinkys will be put between (fig.5). Ask “How is school today? Why?”
This will start a dialogue and invite them in.
5-15 minutes
Invite them into the lesson by asking if anyone has ever been in an earthquake.
Maybe ask them if they have seen them in movies and TV shows. Have them describe the
experiences and discuss, “What are earthquakes like?” Then begin the lesson by asking,
“Do they happen all of a sudden or do they take a long time?”
Take out the fault blocks and explain to them how the normal and reverse faults
work. Ask where the push and pull would have to be on each block to create either a
normal fault or a reverse fault. Once they have it down go over strike-slip fault. Do this
rather quickly as this exercise is very short.
Then start talking about how the energy from earthquakes gets to us. How do
earthquakes, which usually happen deep underground, affect us all the way up here? The
energy gets to us in two different kinds of waves. Ask, "Where have you heard of waves
before?" "What travels in waves?"
Explain about Primary and Secondary waves and, after telling the students how
each wave moves the earth, discuss with them which one the think is more dangerous.
Have a volunteer stand up with you and demonstrate these waves using a slinky.
15-35 minutes
Have the students spread out in two lines as shown in Figure 5 . Ask them to have
the rope in between them at first and try to create a primary wave. It can’t really be done,
its too dense. Then have them create a secondary wave, which can be done in the rope
medium. Next have them put away the rope and use the slinky instead. Have them create
a p-wave by giving the stretched out slinky a push. You will be able to see the energy
propagating through the slinky in a compressional way. Next try s-wave again which
should also be possible. Make sure you discuss how the medium, the flexibility of the
slinky, is what allows these waves to pass. Then have them put away the slinky and in the
middle of the lines of students spread the three-layer medium slinky. Talk about how
different mediums change how the wave goes through. Then use that as an example.
Create p-waves with it and notice how they travel faster in some of the slinkys then
others.
35-45 minutes
Now have the students get out a pen and paper and answer your assessment
questions below. Then make sure the classroom in clean and do your conclusion
Assessment:
Read the questions out loud and have the students answer them on a half
sheet of paper.
1) (Draw them a normal fault on the board) Have them right down if its
normal or reverse, then draw it themselves and label the foot and hanging
wall.
2) We saw with the rope, that some mediums can't produce both waves. Do
you think sand could produce both p- and s-waves? Why?
3) What do you think would be more likely to feel big waves, sandy ground,
or concrete ground? Which would you build your house on and why?
4) Which is the most destructive wave?
Resources/ Bibliography:
http://www.digitalgeology.net/page1.html
http://visearth.ucsd.edu/VisE_teach/lessons/seismic_LP.html
State Standards Covered:
3:1:D "Students know energy can be carried from one place to another by waves,
such as water waves and sound waves, by electric current, and by moving
objects."
Notes and Comments: Please comment here if you have preformed this lesson plan
and have found ways to improve it, effective examples, new ideas for a lesson, etc.