Resources and Tools for Elementary Math Specialists and Teachers

Guess-Check-Improve Strategy: 2.5

This discussion is part of a collection:CCSS Practice Standard 8

This is a highly under-valued problem solving strategy. I always tell students that knowing what doesn't work -- keeping track of it, paying attention to it -- is just as important as knowing what does work. It's a challenge to get them to simply strike out errors, not erase them. On many occasions I've seen students learn more about the math in a rich problem through good guess-test-improve methods than by applying a direct procedural approach. Sometimes that G-T-I strategy is an important step on the way to abstraction and developing the more direct "elegant" solution.

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The G-T-I method is very similar to the method of partial quotients that is used to teach many students long division. In this method students build the understanding of what long division really means before getting to procedural. This method definitely takes more space, but is necessary for building the understanding from 5th to 6th grade.

cmead, I can think of many problems where this strategy leads to more knowledge than the direct approach. In limited space I'll mention one type – where the solution is an acceptable range of values and knowing what's too small or large is crucial. How less strange those inequality relations would seem with more problems like this.