When three of your favorite bloggers all write about the same lesson (Dan, Andrew, Fawn) it is a pretty safe bet that you should do the lesson. I used Andrew’s 3Act video because my students can be pretty green and I might not hear the end of it if I couldn’t find an additional use for all these cups I was bringing into the class.
I don’t have anything to add to what was already said by Dan, Andrew, and Fawn, so I will just share a problem I created that you can put on your midterm that is a slight twist to the presentation of the original problem:
1. How many cups would stack in a 250 cm door?
2. What are the dimensions of the cup? Draw it and label it with the dimensions.
I suppose you could ask for the y-intercept and slope and all that stuff too if you wanted.
Moving on from test questions – The actual lesson went great for me and I am definitely looking forward to doing it again next year. When I did this problem in algebra I had the students make a Stacking Cups comic that was supposed to describe how to solve the stacking cups problem.
I like the comic concept because I think this is a very visual problem, and since I didn’t provide them with actual cups they needed to create their own visuals. I have been trying to get students to give me a visual for every word problem they do this year. My stated reasoning for that has been that visuals help you give a clearer and more convincing justification for your solution.
In order for students to learn how to construct a viable argument and critique the reasoning of others (Let’s hear it for MP.3!!!), we are going to have to have an iterative process on a couple problems where they essentially hand in drafts, and we keep having them make improvements. I think this is a great problem to do for that since it has a couple nice extensions for system of equations (different sized cups) and geometry (here).