Monday, August 31, 2009

M&M Catapult project pt. 1- The catapult plans

This is a fun lesson I've been doing for a couple years now with my Algebra 2 class. This post will briefly explain what the project is about and show how the catapults were made. Part 2 will include the actual project packet, and go into more detail about how it all works.

Each group of students (2-3) gets a small catapult, and shoots M&Ms from it while it is on the ground. They measure how far each shot goes and how long it is in the air and use that to figure out how far the catapult will fire when they place it up on a desk. They place a target where they think their projectile will land, and get points based on how accurate they are. I check in with each group regularly so they aren't getting too far off course. It's probably my favorite project because it takes a large number of the things we've done in the chapter on parabolas and puts it all together, in a "real life" situation. (While firing M&Ms doesn't have much of a purpose, it's pretty easy to get them to understand the correlation to ballistics)

Unfortunately this project does require some setup (making the catapults), but it shouldn't take too long. I bought popsicle sticks, a few small pieces of wood, wood glue and some small clothespins at the local crafts store and used some scissors and masking tape to make this:

If you have Google Sketchup you can see my model of it here.
The plans are (I hope) pretty self explanatory from the pictures above. The base was a small piece of hard wood I also found at the craft store. The clothespin sits on a platform made of four popsicle sticks cut up with scissors. The basket to hold the candy is made out of masking tape. I added the guide rails on the sides to help with accuracy, in the picture directly above I removed one so that you could see the interior better. This year I was considering changing the plans to allow some sort of button to fire it to improve accuracy, but overall if the students were careful they came out with excellent results.
Stay tuned for part 2 which will include the actual project the kids do!


  1. Dude, this is awesome. I can't wait to try this with my students.

    Question: how do you make the basket out of masking tape? Do you just try to squish the tape togther like when you're working with clay at a potter's wheel? (I'm thinking Swayze and Demi Moore in "Ghost")


    - Touzel

    btw, I found your blog through Dan Meyer.

  2. Tear off a length of masking tape that when wrapped around in a circle has roughly the diameter of the Popsicle stick. Leave a little extra to adhere to itself. Fold it hotdog style directly in half, wrap in a circle and lay one end over top of the other so that it sticks. You should now have a short empty cylinder with no stickiness on the outside. Place it on the stick, and wrap a second piece of tape from one edge of the basket, around the back of the Popsicle stick and up onto the other edge of the basket.

    You could also use a small strip of paper taped into a cylinder for the first part if the tape alone is too hard to manage.

    I'm not sure if what I wrote makes any sense. If you're still confused let me know and I'll see if I can make a picture.

  3. Have you tried drilling a hole in the popsicle stick just slightly smaller than the diameter of an M&M? This might hold the M & M in place.

    Also thought that using a rubber o-ring and using a glue gun to glue it to the popsicle stick might work.

    I plan to build some of these M&M catapults this weekend. Teaching unit on quadratics right now and want to try out your project as a culmination to the entire study of quadratics.

    Would be nice to see some actual pictures of the catapult.

  4. I just finished build 10 of these catapults. However, I modified the design slightly and have some other suggestions to help speed up the construction.

    I have glued a threaded nut onto the popscile stick instead of using the masking tape. The nut holds the M&M in place quite nicely.

    Instead of using wood glue I used my wife's crafting glue gun to glue everything together. The glue gun made gluing everything together way faster.

    For pictures of the finished catapult go to

  5. Thank you so much for this! I finally got to use it this past couple of weeks during the state testing schedule. I hope you'll come check how I've modified it a bit.

    I didn't see your rubric until it was too late b/c I was so eager to start, but I'll definitely use it next time.

    Thanks again!!

  6. Do you have a rubric for this project? I couldn't find one. This is going to be a fantastic activity for my honors algebra group.