The results were startling! Of the 20 teachers, 19 solved the problem rather quickly and confidently to arrived at
5 days as their answer. One teacher, the sole kindergarten teacher in the class, rather sheepishly announced: “I got a
different answer. It’s probably wrong, but my answer is 4 days”. All the teachers who had 5 days as their answer used a
two-step process something like this: (1) 4 m − 2 m = 2 m gain per day; (2) 10 m/2 m/day = 5 days. These teachers had
quickly moved from the verbal statement of the problem to a mathematical representation of it and obtained an incorrect
answer. The kindergarten teacher confessed that she didn’t even think about using number sentences (“Because my kids
don’t know how to do that”). Instead, she drew the following picture (i.e., used a pictorial representation; see Fig. 3).
Yes, students must learn to use conventional representations but, perhaps more important, they must learn to choose
representations that fit the situation and, when appropriate, teachers must engage students in discussions of why their
representations are satisfactory and whether those representations would be useful for other related problems. Our
research on this aspect of problem solving is just beginning