Pimp My Catapult

*Fffwwwooooooooooooooooooosssshh* That is the sound of me blowing the dust off of my blog. Welcome back to my little corner of the Interwebs. Between getting married, buying a house and my math programming side project I've had little time to share anything on here, but I'm back in action and ready to start updating more regularly, so here we go...

I've been tweaking my catapult design a bit each year, and think I've finally found the best design to fire accurately(even in student hands).  So if you tried the catapult project last year, but had trouble with student accuracy this post might help if you're willing to give it another shot. If you haven't tried the project yet but want to this year, I would highly suggest using the design and tips below.  Here is the new design:

Highlights:

1)   Mini clothespins give a more appropriate distance and height.

2)   I now make the basket out of a thin strip of paper, complete the circle with a small piece of scotch tape and use a bit of glue to hold the basket on.  Having a basket that is just barely bigger than an m&m laying flat helps accuracy.  Make sure students know to load the m&m laying flat each time. 

3)   Cut off the rounded edge of the popsicle stick behind the basket.  The flat edge helps fire more consistently.

4)   This new firing mechanism allows student to essentially just pressing a button to fire.  There is still room for some error here, so make sure they know to hit the button SLOWLY each time. The back clothespin is positioned so that it just barely overlaps the back of the catapult when it is all the way down.  Here's a close up with the catapult loaded:

 5)   The front of the catapult is tilted forward so that it goes further and not as high.

6)   Okay, so there's no 6 on the picture, but thinking about it now it would make more sense to move the guide rails on the main catapult much closer to the back.

So there you have it. I hope this helps.  Let me know if you have any other ideas for improvements in the comments.

Previous catapult posts:
http://sweeneymath.blogspot.com/2009/08/m-catapult-project-pt-1-catapult-plans.html
http://sweeneymath.blogspot.com/2009/09/m-catapult-project-pt-2-project.html


BONUS:  I let one of my classes build their own catapults last year, and after finishing the project one group decided to come in to my classroom during some free periods and make this ridiculously awesome trebuchet.

M&M Catapult project pt. 2- The project

Click here for the Candy Catapult Project Description (updated)

In all honesty, I have probably always liked this project a little more than the kids, but over the past few years I've improved the delivery so that they definitely get into it. My biggest mistake the first year with this was not giving the students an overview of what they were going to do and trying to let the packet speak for itself. That failed... miserably. Now I give an general overview complete with pictures and a discussion of why the lesson is important beforehand and they seem to enjoy and understand it a lot better.


I think one of the reasons I like this project so much is that it actually works. When the kids are consistent and do their calculations correctly, they will hit the center of the target with ease. It's one of the all too rare opportunities that students get to see that the math they did directly affected something in real life.


Some tips for the teacher:

• I generally work the stopwatch for them. I've found myself wincing at how much the kids think the timing is "fine" when they do it on their own. I'll start a countdown out loud, and if I feel like my button presses weren't as good as humanly possible, I'll tell them not to count the trial. Letting them do it on their own (poorly) could I supposed be a "lesson learned" but I feel like after all the calculations they do, they won't realize what exactly went wrong or take such a lesson to heart. It would probably be worthwhile to let your kids try it on their own first, but keep a close eye on the timing aspect.
  

• Strongly encourage the students to make sure they are shooting consistently before they do official trials, and to start over if their official trials aren't close together. You'd think the bold, caps, and underlining in the description would be enough, but my kids tended to be a bit overconfident and tried to rush through without frequent reminders.

•  This project takes me ~2 40 minute classes based on class size and skill level. I'm sure it could be done  faster with more space and more student independence.

•  Having some backup Skittles might be a good idea in case of allergies or dislikes. (I mean, what fun would it be if they couldn't eat some leftovers?)

I realize that there is a bit of hand holding, some of which could be removed to get kids thinking more on their own (especially if you were to give this to an honors class), but it's mostly to get it to fit within time constraints. As with any lesson or project on here, I encourage you to use and edit this to meet your own needs. Let me know what you come up with or if anything is unclear.

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!