Doughnut Math

My 7th grade math students are currently studying surface area and volume. Over the course of the unit, I've learned these skills are something I take for granted. I started out assuming they knew way more about this than they did. However, we slowed it down a bit, and now they're doing wonderfully. 

Yesterday I had some doughnuts left over from my 8th graders, and it dawned on me that it was a great way to review the surface area and volume of cylinders we'd been studying for the past week or so. 

I cut the doughnuts in half and told the students they needed to calculate the surface area and volume of doughnut (in organized lines of equations) before I would let them eat the doughnut. Talk about motivation. 

Wonderful mathematical things about using a half a doughnut: 

1. There's a hole in a doughnut! They not only had to calculate the surface area and volume for the whole span of the doughnut, but they had to do it for the missing hole as well. This gave them some extra practice and had them thinking of the deeper level problems that we've been solving. 

2. It's a half! Even though they started out calculating the volume and surface area of a whole doughnut, they really needed to remember to halve their calculations. Again, it added a greater depth to the problem. 

3. You get to eat a doughnut! Who doesn't love sugary goodness? Okay, that's not mathematical, but it's true. 

It was a great way for me to check their understanding and progress in our unit. Another one of my happy accidents in teaching. :)