You should definitely shoot candy when you cover projectile motion in Algebra! I got this fun idea from Sean, who even had his students build their own catapults! He’s a rock star. Luckily, our math department already had some catapults that I was able to use. If you want to save time, the catapults were only $7.89 from Amazon and worked great! I used Starbursts instead of the included balls (candy for the win). But students did have to create a tape basket for the shooter since the Starbursts were smaller and were falling through. My students call this the Starburst Catapult activity and many said it was their favorite activity of the year.

This activity follows my projectile motion lesson, which will be very helpful for your students to do before Candy Catapult so they understand what the dilation should be and where it is coming from. After reading Mimi’s comment on Sean’s post I amended Sean’s instructional worksheet (Candy Catapult Worksheet) to have the students do all of the* quadratics* work with **just the time**. This makes it a projectile motion problem, and then they can use -4.9 meters/sec for the a.

**Candy Catapult:**

- In groups of 3 or 4, instruct students to carefully read their handout.
- Students shoot the catapult from the floor and time how long it takes for the candy to hit the ground and the distance their candy travels. Students used their smartphones to time the flights. I tell them to practice and make sure they are getting accurate results. They do not get a target at this stage.
- They use this data to create a quadratic equation of the candy’s flight (in factored form). We used -490 cm/sec as the dilation since we measured in cm.
- They measure the height of a desk and use their equation and Desmos* to find out how long it will take their candy to hit the floor
*from the desk*. - After they find the time the candy will be in flight, they use proportional reasoning to calculate
**where**to place the target. , then we ALL gather around and watch each group shoot, one at a time.**No one may shoot from the desk until all groups are finished**

*I made a Desmos Teacher Activity for students to record their data and then enter the equations that they created from their data. This was a great visual check for them to make sure their equations matched their data before moving on. The graphs also helped them find the numbers they needed when going from shooting from the floor to shooting from the desk.

I did this lesson with all four of my classes, and of course it got better as the day went on. I always feel sorry for my 1st period class. I started out having the groups do all of the work individually, even the final round. But there was really ZERO excitement in that and it just kind of, ended. By my last 2nd two classes of the day I had set up a true, “Final Challenge Round!!” where the entire class watched. I even played Jock Jams to get them all “pumped up”. Oh, the things I do to get high school students energized.

We did everything in an 85 minutes block class. However, I wish I had spend one additional class day after the activity to reflect and even challenge them with variations of the catapult problem to whiteboard with. I need to find giant catapult war related problems! (Or I’m watching way too much Game of Thrones lately). But really, wouldn’t that be the most fun!

Tips for Success:

- MOST IMPORTANT!! Do the final round at the end, with everyone watching each other so they can root and especially heckle.
- Play music during the finals. (I used a Spotify Jock Jams playlist.)
- Print out a LARGE target! I found a picture online and used 4 sheets of paper.
- Emphasize consistency, consistency, consistency.
- Use centimeters to measure, and -490 cm/sec for the dilation.
- Remind them to sure the are consistently measuring in cm, not flipping the tape over and ALSO measuring in inches. True story.
- Bring prizes for winners
- Spend an additional day reflecting, and even give additional problems to solve.

If you do this activity and create a reflection activity or additional problems I would love to see them! 🙂

**Enjoy the action!**

Resources:

Candy Catapult Worksheet (amended from Sean)

This looks awesome! I am definitely doing this next year!

This is not only a fabulously well thought out activity, but also a brilliant use of Desmos Activity Builder that I hadn’t thought of: A tool for recording collected data. I now have such a great hook for getting our science teachers using Desmos as well as our math teachers.

Pear Deck is also an awesome program for science teaches. They can collect data in class and then work on a doc online at home.

I am wondering how much background work they did before this.

I got the formula to be h(t) = 0.5gt(T – t), which is so neat it’s almost unbelievable.

after wasting time finding the function for H(x)

There is of course an assumption of constant horizontal velocity.

ps. The Desmos page shows h(x), not h(t), even though the axis is labelled “time”

Oh thanks! Good catch with the h(t). I’ll need to test the t. Sometimes Desmos acts up when the kids put in another variable other than X. I know what to do but it confuses them.

They had done some intro work with quadratics but nothing extensive before this. I liked how that went, but do wish I had followed up afterwards more to strengthen it. I also loved how simply the formula worked out!

I tried it with the t and it was ok. If there is f(x) and t in the expression then Desmos just has its puzzled look.

Did you have more than one catapult?

Yes, I had one for each group. 🙂

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Hi Julie 🙂 Thank you for this great idea! I’m pretty excited to try it!