This was a project for a grade 1 class that has been exploring potential and kinetic energy. The idea was that we would all build the same basic chassis, then kids could build on to it any way they liked--scrap wood, bottle caps, LEGO people etc... Later on, we rolled the cars down various ramps and measured the amount of kinetic energy by how far it bumped a box. More on that at the end...
Step 1: Tools and Materials
-I cut the wheels from MDF on my X-Carve CNC machine, making sure that the holes in the centre would be a tight fit for the chopsticks that would be used as the axles.
-The body was a block of 3/4" plywood 10cm x 4.5cm. I chose these dimensions so that the final car would fit well on a pine derby racetrack that I inherited.
-Two tongue depressors fit on the sides and hold the axles in place. They are 3/4" wide so they fit nicely on the sides of the block. They are just thin enough that the kids could easily punch the holes in them with the hole punch.
-I was lucky to discover not only that the hole punch would easily punch a hole through a popsicle stick or tongue depressor, but the hole is just slightly larger than the chopsticks so they can spin freely.
-The tin snips can cut through the chopsticks easily. No need for any sort of saw.
-The sandpaper was there to smooth out the block and the wheels and clean off any glue at the end.
-PVA glue worked fine. We used masking tape to hold things in place while it dried.
Step 2: Sand the Blocks and Wheels
There wasn't a lot of sanding to do, but I wanted to give the kids a variety of tools and familiarise them with the process of making stuff which so often (unfortunately) does involve sanding.
Step 3: Punch Holes in the Ends of the Tongue Depressors
I am just so thrilled to have discovered this. It's one more step that they can do for themselves. While I do sometimes use drills with the younger kids, it needs to be 1 to 1. This is so much easier to manage.
I have since bought a ton of nylon nuts and bolts to fit in those holes for other projects. More on that in an upcoming post...
Step 4: Cut the Chopsticks in Half and Sharpen the Ends
The kids cut a chopstick in half to make two axles. Sharpening the ends just a bit made them easier to slide into the holes on the wheels.
Step 5: Glue on the Sides
After putting the glue on, sliding a chopstick in place helped make sure they were aligned properly. We used masking tape to hold it all together while it dried
Step 6: Add the Wheels
The wheels fit pretty snuggly on the axles, but we added a drop of glue just to make sure everything stayed together. After snipping off the excess, some kids gave it a few taps with a hammer to flatten it down a bit better or buffed it with the sandpaper.
Step 7: Dress It Up
I keep a box of scrap wood for the little ones that is full of small pieces that don't need to be cut down any more. We got a surprising variety of cars from all of the random shapes that were in there. The mass of each car was sufficiently different that when we rolled them down the ramp it was measurable.
Step 8: Testing
We put the metre sticks on either side of the ramp so the cars wouldn't roll off. We put sticks on either side of the pizza box so that it would slide straight. The kids set the box at zero and then measured how far it moved when the car rolled down the ramp and bumped it. Then were able to compare all of their cars, along with various other things--sliding blocks, rolling marbles, Hot Wheels cars etc. then graph it back in the classroom.
Step 9: Next Steps
i inherited a 16m pine derby racing track from a friend at another school. We chose the dimensions that we did so that the cars would fit on here and we could have races. In the future, I hope to open this up a bit more and see what other sorts of designs the kids come up with. We will probably have a tournament of some sort.
Thanks for reading!