A New Car Plan

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A few years ago, I went to a lot of work to design a car project for my class. (You can read about the design process and/or just read the tutorial for our final design.) It is a fine project – pretty doable for the kids, decent though not great results. But, it’s a ton of prep work for me.

I’ve just tested the Basic Rubber Band Racer kit from TeacherGeek, and liked it a lot. It yields a better result and is near zero prep time. It’s very manageable for young kids to do, and I like TeacherGeek’s recommendations for a build process, where first you build the body without wheels, and test sliding it down a ramp, then add the wheels and test that on various heights of ramps and graph out how far it travels, then add the rubber band that you can wind to “motorize” the car.

Here’s a video of the basic car:

Here’s a video with the rubber band engaged.

TeacherGeek sells single rubber band racers for $8.00, or 10 kits for $65. Or on Amazon, it’s also $65 for 10 Rubber Band Racers. That’s outside my price range for my class, but they do also sell bulk components, so I priced those out compared to the DIY car design we have been using. Note, for our current design, for the bodies I use corrugated plastic that I happened to have laying around, so it’s “free” for me, but I don’t know what it would cost to buy.

Current design:
Body = free
Wheels = $23.70 for 100 = ~ $1 per car
Dowels for axles = $13.50 for 100 = 25 cents per car
Retractable badges for motors = 45 cents per car
Plus half a straw per car plus tape and hot glue = ~10 cents per car
$1.80 per car plus lots of prep time: cutting out bodies, cutting dowels, cutting straws, putting glue squiggles on wheels for traction

TeacherGeek rubber brand racer, if I buy bulk components
Body = 9.50 for 20 plates = 95 cents per car
Wheels = $16 for 40 = $1.60 per car
Dowels for axles and to assemble car = $8 for 50 = 50 cents per car
Rubber bands for wheel traction = 1 pound (~145 bands) for $13 = 20 cents per car
Clips for holding/winding rubber bands = 8.90 for 100 clips = 9 cents per car
Slide stops for stopping a dowel from sliding out of frames  <5 cents per car
Rubber bands for “motors” = free (usually have plenty laying around)
$3.39 per car plus minimal prep time of cutting dowels and slide stop.

Hmmm… that cost is too high for my class budget. Back to the drawing board: my next attempt: I have these plastic boxes that Starbucks protein plates come in… I wonder if those could be car bodies? Could I use these TeacherGeek wheels for the front wheels? They’re much cheaper than the red ones, but also much smaller – would it work to have that much of a size difference between front and back wheels? I’m off to experiment…

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