So the next day the kids are coming in, having found the areas for all rectangles with a perimeter of 56 units. They had all drawn and counted out the squares. We went through answers together, and then one student pipes up and says,
“Hey. I think I found a shortcut for finding how much space they take up. You can multiply the two numbers together.”
“Hmm,” I say. “Are you saying that you can multiply the two dimensions, and it will give you the space it takes up – its area?”
I’m doing jumping jacks inside with this “discovery,” but I play it cool.
“Kids, take out calculators and see if his theory is correct.”
Sure enough, wouldn’t you believe it!?
Well, then, we can take a look at how we write dimensions in the first place: 3×5, 6×8.
“HEY! That’s the multiplication sign!!”
Why yes, it is, she thinks with a sly grin.