|Photo: Courtney Day|
Instead of using traditional mathematics vocabulary, the students explained an exercise they had done in class using blocks. Stack four blocks to the right and you have positive four. Stack two to the left and you have negative two.
But what if you have four blocks on the right and two on the left? Your answer is positive two, but you get there not by subtracting a positive number but by adding a negative one. Algebraically, the expression is 4 + (-2) = 2.
Moses waited patiently while the students explained the exercise and then described the outcome using mathematics vocabulary. Occasionally, he injected questions into their dialogue, but mostly, he just listened.
Only after the students solved the problem did his teaching begin.
"In arithmetic, it's the operation which pulls the direction of your bounce," Moses said. "It tells you which way to bounce and gives you direction — bounce this way if you're adding, and bounce this way if you're subtracting."
This, Moses explained, is a big difference between arithmetic and algebra.
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Source: Mansfield News Journal