Friday, January 31, 2014

Cross multiply

When I think about the problems kids these days have with math, it can be summed up with "cross multiply."

When I teach this concept (with proportions)I stress that it is two fractions with an equal sign in the middle.

Somehow, the importance of that equal sign is never learned. If you have 2 fractions with a + in the middle - or a- or a *-doesn't matter. Two fractions means cross multiply.



Kate Brainerd said...

Wow. I have not cross-multiplied, myself, in many years. This was actually a refresher for me. Maybe you should give up on these irritating kids and start an on-line series like Khan Academy or something. I would be all over that.

Pissed Off said...

I have felt your pain for years and still feel it. Sometimes it even comes through in a pre calc class.