The teacher asked the students how they would solve the example. He deliberately had the students write a mistake on the board (3/4 + 5/6 = / (4 + 6)) and then showed them why they couldn't do it that way. I wondered how many students helped understand why the fractions didn't add up like that, and how many students just messed up their heads. They immediately calculated the example correctly and wrote down a procedure for it. For an hour, I looked at students who were good at math.
I wondered how many students helped understand why the fractions didn't add up like that, and how many students just messed up their heads.