In my last class I focused a lot on proportional reasoning, and at the end of March I wanted to give the kids a project that would be rich with a lot of different examples of the topic.  My original idea was to do a theme based on turning a beat into a song, but it seemed contrived.  Frustrated, I headed down the street to the only empty grocery store, and thought about how all the prices there were really high.  Suddenly a flash of insight hit.

The students can take down their expensive local grocery store!

Kids can imagine a product that they like to sell, and then look up how much cheaper it would be at a warehouse store, and compare the difference in prices.  Then students can use evidence from their local store to estimate how much money they would make from a day of selling the products, and then scale what the products would make over a month.  I went back home and scribbled a bunch of notes about the idea with a Doc-Brown-Esque level of enthusiasm, but I didn’t really put together a polished task until last week.

Download (PDF, 939KB)

Here is what I gave kids, although I really wish I could have made it better.

What I like about it:

  • It is a pretty straightforward task whose end goal makes enough students that all students can really understand what their end product should mean.
  • Students need to use proportional reasoning in so many different places that there are countless numbers of places to discuss it.
  • Since all students can do different products at different stores, the entire class can come up with different project results so there is no copying fear.

What I wonder about:

  • As a project to help kids express their proportional reasoning, should I have asked them to explicitly demonstrate two or three different ways of finding a number that would proportional to some other set of numbers?  If so, which ways should they all HAVE to know how to do?
  • How could this be better?

IF you can give me any feedback about the project, I’d appreciate it if you mentioned it by commenting on the google doc of this here.