I thought helping the twins' with math would be my downfall, but you guys, 8th-grade science! Last week the kids came home with a project for their science classes. They had to make a mousetrap car that would move over 4 meters.
They drew plans, they modified those plans, and then last weekend I set about helping them construct their car (they decided to work on this project together, and because they are in separate classes at school they were allowed to do this). I wanted them to do the work but wanted to help them where possible, so we all sat down together and watched YouTube video after YouTube video, we found tutorials on Instructibles, and we started building car number 1. Fail. We trashed it. We started on car number 2. It was about 8 pm Sunday night when we finished it and they had to turn in their prototype the next day for evaluation and to see what they could do to improve it. The car simply spun in circles or flipped over, it wouldn't move in a straight line. So again, Monday after they brought it home from school we trashed it.
Now, before sharing these instructions, I'm not a science teacher, I don't pretend to play one on-line, I'm just a parent who was trying to help my kids with their project and this is simply what worked for us. If you have any suggestions for readers on how to make the car even better I would love for you to leave those in the comments, feel free to leave links to your own mousetrap car projects that worked too.
So we left it for a day to get over our frustration before tackling it again Tuesday night. We decided to start completely from scratch. Flynn's teacher had suggested using larger wheels; we'd initially tried using juice and milk bottle caps because they wanted the projects to use as many recycled items as possible. But, I headed to the store and splurged on blank CD's and we started again.
Their new car with a new design and new materials traveled about 4 meters on the first try, and then 6 meters on the second try (before crashing into the front door). So, I'm here to try my best to help others by offering what did and didn't work for us.
Let's start with what didn't work for us:
- A car that was light enough to flip, you need more weight on it (more wood, washers, whatever works).
- A shorter car - that again goes to the above, a longer car with a longer lever will run further.
- Bottlecap wheels - I'm not sure what the reason was, but we tried it twice and even with electrical tape on them, it just wouldn't go as it should
So let's break down some things that we changed when we did our new design and we finally got a car that would run in a straight line and over 6 meters.
WHAT YOU NEED:
- Wood rectangle (plywood is just fine)
- Popsicle sticks
- Wood dowel rods 1/4" wide (either one long one you can cut or a couple of pre-cut ones)
- Hot glue
- Washers (make sure the hole fits over the wood dowel rod as snug as possible)
- Cord or rope
- Eye screw
- MORE HOT GLUE - I can't stress this enough
- Straws - I've posted a link at the bottom to what we used that fit perfectly over the wood dowel rod giving it enough space to rotate inside
- Electrical tape
- CD's or DVD's
I've provided a video below so you can see how it will work, but here are images of the top and bottom of the car so that you can see how to assemble it.
This project needed to be doable for the kids, so we tried to keep it as basic as possible. One of those issues we faced was getting the axle (the wood dowel on the back wheels) to rotate. The second car we had tried we saw a tutorial for a small juice box straw that had a wood skewer running through it. It just didn't feel strong enough though and when the teacher suggested bigger wheels I knew we had to go bigger everything. Which also meant finding a larger straw that would fit a dowel rod through it, most standard straws are simply too small. And then in the middle of our dining table I spotted it. I keep a rotating tray in the center of our dining table with things such as napkins, honey straws, salt and pepper, and straws of beaded flavoring for milk (which I'd bought as a special treat one day and there was still two leftover). Drink up kids, we're using those straws.
Now, here's the link for the products we used (these are Amazon affiliate links, it doesn't cost you any more to buy through them though).
And here's that video I put together so that you can see it running. I had to cut the video short because it was going to run into me, but it ran over 6 meters.
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