Building a Car

This project is a simple car with rolling wheels and affordable parts that a preschooler and parent can make together, or an elementary school kid can make with minimal assistance. Here’s a video tutorial, or the instructions are all written out below.

Supplies Needed, per car: template printed on cardstock; two six-inch lengths of 1/4 inch wooden dowels; 1 plastic straw; 4 wooden wheels*; optional: 4 CD’s.

Equipment Needed: hole punch, scissors, glue, rubber band, paper clip

Building the Basic Car

  1. Print template on cardstock. (There are two cars on each sheet, so you’ll cut the sheet in half before the next step.)
  2. Fold up one of the long sides along the dotted line. Fold it a second time. Repeat on the other side.
  3. Punch holes where the four dots are.
  4. Thread the dowels through the holes – these are your axles.
  5. Put the wheels on the axles.
  6. Optional: you can cut straws (~1.25″) to be spacers to help keep the wheels equally distanced from the side walls of the car.

Take the car for a test drive. How’s it working?

If the axle isn’t turning well, you may need to enlarge the holes just a little. You can ream them with a paper clip.

The wood wheels don’t always fit perfectly. (I usually have a few in each bag where the hole is too small to go on the dowel well.) If they are loose and falling off, you have a couple options: you can add a little tape to the ends of the dowels to hold them in place.

Or you can glue them on. I use a water-based school glue (like Elmer’s), so if I decide I want to take the wheels back off the axle to re-use in a future project, I just have to soak them in water for a minute or two to soften the glue and I can take them back off.

If the wheels are slipping, you could choose to drizzle some hot glue around the rims to give them traction.

Add Bigger Wheels

Take the wheels off the car, and glue them to CD’s. (Be sure to center them perfectly or your car will roll in a really wobbly way.) Then re-assemble the car.

Now test the car again. Help your child notice how much farther the car rolls now with each push.

[Math Trivia for Grown-Ups: In one rotation, a wheel travels as far as its circumference (diameter times pi). So, a 1.5″ wooden wheel travels 4.7.” A CD, which is (coincidentally) 4.7″ in diameter, travels 14.7″ per rotation.]

Add a “Motor”

Attach a paper clip to a rubber band. Loop this around one axle. Then stretch the rubber band up to the other end of the car (passing under the second axle) and clip it there.

Now, turn the back wheel round and round to wind the rubber band up around it. When it’s wound up several times, set it on the floor, and let go. As the rubber band unwinds, it will propel the car across the room.

Test it and see how far it travels!!

*Supply Notes: I like the wheels from Teacher Geek – these pair with 5mm / .2″ dowels. They work well and are a lot cheaper than the other options… though they smell bad for some reason. I have most often used these 1.5 inch wheels, and occasionally these. Those links are Amazon Affiliate links (I get a small referral fee if you click on those links and then buy something) but you can find similar wheels at Michael’s or other craft stores. You could cut your own wheels from cardboard. I don’t do this because if I have 36 kids making a car in one day, that’s 144 wheels I’d have to cut! Or, you could probably use plastic or metal lids glued to dowels. You’d just have to be sure that the dowel was centered on the wheel so it would roll smoothly.

We build this car in our Engineering Unit when we study wheels and axles as a simple machine. I’ve been working for years to find a workable design for a car model that is do-able for little kids and has accessible, affordable supplies. Learn more about my past design process here. Here’s our Cars Lesson Plan.

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