Math Monday -- In Which the Lesson Doesn't Go As Planned...And is a Success

It's Math Monday! 

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for the Math Monday link up!

We were going to begin a big estimation problem (How Many Books Are There in Ms. Hahn's Classroom?), so I chose my math workshop opener from Estimation 180 -- days 28-30, a sequence of toilet paper estimations. I knew exactly what I wanted to get out of this opener, and I expected it to be quick.

What I didn't expect what that my students would get mired down in a dis-remembering of what exactly perimeter, area, and volume are, and why the square footage fact we jotted down from the packaging shown in the answer of day 28 could not be used as the total length of the toilet paper on the roll on day 30. Maybe it's because we were talking about squares of toilet paper that their brains convinced them that square feet would be okay as a unit of length.

I let them struggle through misconceptions like squares and cubes are the same and you use 3D measurement for square feet. It was one student's tentative sharing of a rhyme she learned at her old school, "Perimeter goes around, but area covers the ground" that finally turned the tide away from the confident assertion of another student that square feet is a measure of length. You should have seen the lightbulbs go off above the heads. Boom. They had it back. Area is LxW (2D), volume is LxWxH (3D), and perimeter is S+S+S... (a measurement of length). Whew.

I've written often about the difference between leading the learning and following the learning. The importance of following is something I have to remember over and over again.