This week I gave my grade three classes a problem solving question that was a double-digit by single-digit multiplication problem. This level of problem is clearly above the mathematics for grade three here in BC, but I knew it was a good problem because it got the students thinking deeply about multiplication. A number of misconceptions surfaced during the lesson and we were able to talk about those both during the working time (when I visited the small groups) and in the sharing solutions time. The problem was this:
Clara planted 13 pots of flowers. She put 6 flowers in each pot. How many flowers did she plant?
The students used a variety of tools in working to solve the problem. They used tally marks, drawings, hundred charts, 100-dot arrays, and blank number lines (student drawn, and only important numbers marked). Some used only symbolic form (digits only) but there were a number of different strategies used to add up all of the flowers.
This problem is “rich” in that, although there is only a single correct solution to it, there are multiple ways to arrive at that solution.
I like to tell students that being able to come up with different ways to solve a problem is like flexing math muscles, and that it makes them “strong like bull” (which I say in a heavily accented voice while I strike a “he man” pose! The kids love it, but more importantly, they get what I mean!
Help your students become “strong like bull” by having them do some problem solving.