Activity
Preparation:
These steps would be difficult to do as a class. If you
have the equipment necessary and a relatively small
class, it could be done. Perhaps a wood shop teacher
would be willing to help you out.
If you are buying a kit, all the wooden parts are included
and they are already cut to size. So you just need to
connect them. If you don't have a kit, prepare the wooden
parts as follows:
1. Cut two square pieces from the 1/8” balsa wood
(3.5" x 3.5").
2. Make a 3/8" hole in the center of each square.
3. Cut four squares 1" x 3 7/16” from the
1/8” balsa wood.
4. Cut a 3/4" piece from the 1" wood dowel.
Make a 3/8" hole in the center of it. Insert a 6" long
3/8" wood dowel in the hole, and apply some glue.
Place it about 2” from one side of the 3/8” dowel
and wait for it to dry.
5. Make another hole with the diameter of your rod magnet
in the center of the larger wood dowel piece for the
magnet to go through.
Wood dowels after completing step 4 |
|
Wood dowels after completing step 5 |
|
If
it is necessary for you to prepare the kits yourself,
the process could be streamlined. Try cutting multiple
pieces of the same size from a large sheet, minimizing
your cuts. Once the kits are prepared, you can begin
the lesson.
Day
1
Construction of the generator: These
steps are taken directly from the website, as is the
picture.
1. Insert the magnet in the hole of the wood dowel.
Center it and use some glue to secure it.
Note—make sure one group has the magnet of differing
strength.
2. Use one large square balsa wood and four smaller rectangular
balsa woods to make a box.
3. Insert your wood dowel into the hole in the center
of the box. At this time the magnet is inside the box.
4. Place the other large square to complete the box.
Apply some glue to the edges and wait for the glue to
dry. By now, you have a box and inside the box you have
a magnet that can spin when you spin the wood dowel.
5. Wrap 200 turns of copper wire around the box and use
masking tape to secure it, leaving both ends free.
6. Remove the insulation from the ends of the wire and
connect it to the screws of the bulb holder or base.
7. Insert the light bulb
8. Spin the wood dowel fast to get the light. Here is
a picture of a completed generator:
 |
If
students finish before the end of the class period,
allow them time to work with their generators. Ask
them to think about a testable question that they have
about the generators. In other words, ask them to hypothesize
about what they could change in their design in order
to alter the output of the generator.
Day
2
Experimental
Design
1. Each group should come up with a testable question.
There are not a lot of variables to change, so some
groups will be testing the same thing, which is OK.
Some possible variables include the number of turns
of wire, the strength of the magnet, the diameter of
the wire, and the speed of rotation of the magnet.
Work with each group and ask them what question they
plan to test.
Note—One group will have the magnet with a different
strength. This group will not be able to rebuild their
generator with a different one. I would suggest pairing
this group with another one that has a regular magnet,
and having them design a slightly different experiment.
They will already have two different generators of different
design, which would make testing the effect of magnet
strength pretty easy. For that reason, I suggest having
them test this effect under different conditions. Both
groups should change the number of turns, and then test.
Then both groups should change wire diameter, then test,
etc.
2. Once they have a testable question, based upon their
previous experience with the generator, each group should
form a hypothesis. Try to make these hypotheses as specific
as possible. For example, if they are testing the number
of turns of wire, will doubling the number of turns double
the current, or will it quadruple it? Don’t just
say it will increase or decrease.
3. Again, check the progress of each group, and then
ask them to write down the steps for an experimental
design. Things to keep in mind while designing their
experiment:
a. What are the independent and dependent variables?
b. If one of your variables is the amount of current
generated, how will you test and record this?
c. What tables, graphs, or charts might be useful to
design now in order to better organize your collection
of data? How many data points are necessary?
d. What results do you expect to see?
4. Monitor each group, and make sure that they have a
workable experimental plan.
5. Once each group’s plan is checked, allow them
to begin experimenting. They should have time to begin
on their experiments, but will most likely not finish
them.
Day 3
Experimenting and Closure
1. Students can begin the class where they left off
the day before. Monitor the class, ensuring that they
are staying on task, and asking any questions that arise.
Make sure that students are collecting enough data, and
arriving at specific conclusions.
2. As groups are finishing, they may begin writing conclusions.
Was their hypothesis supported or not? If not, what happened
instead? What other questions arose while conducting
this experiment? How could you test these questions?
3. Discuss the results of the experiments as a class.
Make sure that the main questions from the objective
are answered. What is the effect of more turns? Stronger
magnets? Different diameter wire? Can we write a formula
to summarize these results numerically?
Embedded
Assessment
This lesson can be assessed in many
ways. I would suggest a short quiz on the information
gathered as a class a few days after this lesson. Also,
a formal written lab report should be completed in
some format, because it will be necessary to measure
the first objective. This should be in whatever format
you have used with your students in the past. There
is a laboratory grading rubric available on the website
that might provide some ideas.
|
Embedded
Assessment
|
