One of the things that doesn't get taught as well as it should is the practical application of math. At one time I worked for Panasonic in a still-being-built picture tube factory. One of our tasks was to measure the approximate capacity of various tanks--Probably at least 100 tanks overall.
People were using various methods. Tanks ranged from 20 liters up to 2000. We didn't have all the equipment we needed. We had unmarked buckets, 3 liter pitchers, metric scales and tape measures.
I saw various methods used-The most common was "3 liters, 6 liters, 9 liters, 12 liters....36 liters...Crap, I lost count". A few knew that a liter of water weighs a kilogram, and tared out a big bucket, filling it 10 liters at a time. A couple used the 3 liter pitcher to mark 10 liters in the bucket, then used the marked bucket.
The vast majority of tanks were either rectangular or cylindrical. To me the obvious method was to measure, and use 6th grade math (Pie are square, base times height) and metric system to calculate.
Reaction was varied. Some people didn't believe me (usually the 3/6/9 oh, crap people). Others remembered the formulas, but didn't quite understand that this is where they applied. A few had a "Duh--Why didn't I think of that" reaction. It seemed incredible to me that I was the first to think of this, with that many people spending that much time.
I think this is a failing in how things are taught. Kids should learn these things hands-on, by measuring things around the classroom. Maybe I'm strange, but I'd have an easier time learning the concepts if I was handling things, and measuring them. Have the class figure out the capacity of the wastebaskets, desk drawers, the room... I know that not all concepts can be taught this way, but wherever they can, they should.