Salt Lake City Conference Exhibitors Motor Mania - International ...

Design a Prototype Model
None of the students have previously designed or
constructed a model car as complex as needed for the
Grand Prix. When asked to make design diagrams of their
cars, students focus on the color of the car and naming
it. Students need a hands-on experience with a prototype
model of a car before making more advanced design
diagrams of their cars—diagrams showing designs that
can overcome particular challenges dictated by a specific
geographic region. As a result, students should first
construct the basic structure of a model car that is free of
battery-operated wiring.
Construct a Prototype Model
Each student needs to have his or her own model car, but
it is important for students to work in teams as they test
and modify their cars in order to mimic the team approach
commonly utilized in technological design, construction,
and testing. Teams consist of four students, and each
team has its own car. For easier management, students
are provided a set of identical supplies to work with at
first. Supplies for a prototype model can be purchased as
a kit through a science catalog for less than $6 each, but
the prototypes can easily be constructed from parts less
expensively. The chassis consists of a 15 cm. plastic ruler.
Wooden wheels of various diameters are used. The front
and rear assemblies are primarily plastic straws that have a
larger diameter straw attached to the chassis with a rubber
band and a smaller diameter straw inserted inside the larger
to simulate an axle and its housing. Small plastic caps on the
ends of the smaller diameter straw hold the wooden wheels
in place. Materials are selected to minimize safety risks. The
most expensive component of the cars is the wooden wheels,
which can be purchased from arts-and-craft stores in bulk
and saved from year to year for reuse. Straws will need to
be replaced each year, as they suffer wear and tear through
repeated use. The school cafeteria and/or local restaurants
may be willing to donate these in various diameters. The
small plastic caps can be omitted. Instead, layers of smooth
electrical tape can be wrapped around the straw ends to
hold the wheels in place.
The students are provided time to build a prototype that
matches their design plans, and they frequently adjust
their design plans based on their construction experiences.
Students are encouraged to share ideas with each other
about different configurations, and the teacher provides
additional support either by asking teams to send a
representative to another table to gain ideas or by directly
sharing ideas with students. For example, the students may
need direct assistance with attaching the front and rear
assemblies to their chassis in a manner that still allows the
wheels to freely move and travel in a straight direction.
Rubber bands attached to the axle housing are a useful tool
for this. Students come up with multiple configurations
of rubber bands to minimize friction while maintaining
equal balance within their prototypes so that the prototype
moves in a straight direction. Additionally, students use
the Internet and texts to explore how prototypes of fourwheeled
vehicles can be constructed. Through construction
and experimentation, students learn about the role of
science in automotive engineering. Once built, students test
their prototype models.
Design a Model to Meet a Particular Challenge
One of the first challenges the teams face is designing a car
capable of traveling across the parking lot in Los Angeles,
CA. Teams know that their cars will move if pushed by hand
or by rolling down an incline, but the challenge of moving
their cars on a flat surface perplexes them. Teams discuss
how they can potentially power their cars. One team plans
to use the force of air released from a balloon connected to
a straw to push their car. Another team asks about using a
motor and incorporates this into their plans. Teams share
their plans, and the idea of using a motor is quite popular
among the groups.
Implement, Evaluate, and Redesign
The teams then build model cars based on their designs
for moving the cars across the parking lot. As students
begin to implement their plans, they find that the plans are
not detailed enough. Students eventually figure out an
effective design for their cars through several cycles
of implementation, evaluation, and redesign; but this
takes time.
Students are provided with wire, a motor, and a battery.
From previous experiences, most students know that wire
has to connect a battery to a motor in order to make the
motor’s axle spin, but this is where their understanding
ends, even though all have had a previous experience of
using a wire and battery to light a lightbulb at an earlier
grade level. The greater task is figuring out how to connect
the wire. Through trial and error, students test various ways
of attaching the wire to the battery and motor. Eventually
the idea of a complete circuit is constructed through their
experiences. The students name complete circuits “loops
of wire” and incomplete circuits “broken loops of wire.” At
this point, the students correctly explain during “think, pair,
and whole-class share” that electricity flows from the battery
9 • The Technology Teacher • February 2008