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The students are first handed an activity packet which includes
the following:
- One "Domino Dealer" toy with batteries;
- A cartridge for the toy filled with plastic dominos;
- A reading packet that includes various articles on "reverse
engineering", toys and engineering; and
- A packet of related mathematical, scientific, and technological
information that will help the students better understand
mechanical advantage, gear functions, and transfer of power
through a power train.
The class is challenged to calculate the speed of the mechanism's
DC motor. The teacher groups students in teams of two. Students
are instructed to start reading their materials, collecting
pertinent information, and organizing that information in
the form of a design portfolio. I prefer to follow design
loop format which includes a) defining the problem; b) brainstorming;
c) researching and generating ideas; d) identifying criteria
and specifying constraints; e) exploring possibilities; f)
selecting an approach; g) developing a design proposal; h)
making a model or prototype, i) testing and evaluating the
design using specifications; j) refining the design, and k)
communicating processes and results. This part of the activity
takes approximately two 80-minute block periods. The students
are not allowed to disassemble the toy. I have some mechanisms
already totally disassembled for inspection.
Some items needed for the students to be successful at this
activity are:
- stop watches;
- magnifying glasses; and
- rulers.
Once each group has found the speed of the motor, the group
posts their findings on a board along with the other group
findings. The real learning begins at this point. Students
will start to question each other as there may be different
answers derived. Once all groups have posted their answers,
it is a good time to reorganize the class and ask the groups
to defend their findings. When the smoke clears, give the
correct answer, and explain how that answer was found. There
are many different ways to solve this problem. I encourage
the students to "show me" other ways to find the
same answer.
To add some excitement to this activity, I distribute another
challenge activity that has the students "play"
with the mechanism to design a system that will make the mechanism
set-up the dominoes in a crooked line and at the end of its
travel, knock the entire line down. This takes another set
of two 80-minute block periods. This design work is also documented.
The end results of both of these activities are carefully
thought-out and documented, not at all "guess your best."
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