Toothpick Toy Cars

thingiverse

https://youtu.be/fo5cxeqcE4E This is a design engineering project for an 8th grade class studying force and motion. They will design the body of a car that will run on some Hot Wheels track. The round toothpicks will be used as axles for the car. A hole 3 mm in diameter through the body of the car, printed on its side, will fit the toothpick axle perfectly. The wheels will have 2.2 mm holes to accommodate the toothpicks. A larger hole (2.5 mm) in the wheel will also work if you use a bit of clay to hold the wheel in place on the axle. I bought a box of Hot Wheels track for cheap on eBay a few years ago. This project was successful. The students were able to make cars that run fast on the Hot Wheels track and measure their speed successfully. Getting the wheels onto the toothpicks is a bit fiddly. A tool to ream out the hole in the wheel is useful, and they don't manufacture toothpicks to a high standard of uniformity, so some were square or thicker/thinner than average. I ended up putting all the wheels on, which didn't take a lot of time. If the students do it, watch out because they will tend to try and push the toothpick straight into the hole and stand a good chance of snapping it and maybe stabbing themselves. Holding the toothpick near the end going into the wheel and twisting works well. Standards NGSS Overview and Background Students will design, print, and test a vehicle that runs on Hot Wheels track using round toothpicks as axles. Students will measure the speed of their toy cars accurately. This lesson was part of an 8th grade unit on force and motion. A student worksheet is included in the files section. Lesson Plan and Activity Acquire some Hot Wheels track (can usually find on eBay) and round toothpicks from a grocery store. Print wheels ahead of time and check that the toothpicks fit tightly into the hole. Adjust size of hole if necessary to ensure a perfect fit. Have students use Tinkercad to design a car or other vehicle. It's easier for them to let them design the vehicle any size they want, then shrink it down. Shrink the vehicle to Hot Wheels size so it'll fit on the track easily. A width of 33 mm is fine for this purpose. Turn the car on its side and insert two 3 mm tunnels to accommodate the toothpick axles perfectly. Print the cars. Assemble the cars by adding wheels and axles. If the students are assembling the cars, snip off the pointy ends of the toothpicks so they don't accidentally impale themselves. Test the cars on the track. Have the students measure the distance and time for their car going down the track and calculate the average speed accurately. Materials Needed Round toothpicks from a grocery store, Hot Wheels track.