Originally Posted by
Tonus
It's an attempt to teach bad students how to think the way good students think. While obviously that example is terrible, the better math students do tend to do mental math by breaking things down into simpler problems... for example, I've had kids who were amazed that multiplying 5 is the same as dividing by 2 them multiplying by 10, but to best students that is obvious because they've figured that out (or to do a 20% tip, double it and them divide by 10, etc.).
Whether this method works is highly questionable. What separates math students at the elementary level is like 99% about student engagement and effort. Students who are active, try to see patterns and push the envelope, develop their own shortcuts for things, etc. will always do better than the ones who just sit there and wait for the teacher to spoonfeed them answers or memorize a bunch of steps.
I honestly think that the issue is not the teaching method, it's that we're too easy on kids in the US when it comes to math. We don't demand adequate mastery of a topic before students are allowed to progress to the next one.
It's crazy to say this but I'm dead serious: I think we'd be better off if instead of cramming algebra into the brains of unprepared teenagers, we instead demanded absolute mastery (i.e. 80-85% correct on a test) of grade school math as a prerequisite for high school graduation. Addition, subtraction, multiplication, division, negative numbers, percents, decimals, fractions, word problems with statistics in them ("one third of blah and 20% of blahblah").
It's amazing to me that the majority of adults walk around with opinions and thoughts in their heads about how the world works, yet then cannot, CANNOT understand the simplest of articles with a few statistics in them. I don't get how they even think that their opinion should even matter when they are so clueless.
Again, crazy to think, but that's actually a much higher standard than our high school grads are held to right now.