Jessica Blanchard:

Rick Burke remembers looking at his elementary-school daughter’s math homework and wondering where the math was.
Like many Seattle schools, his daughter’s school was teaching “reform” math, a style that encourages students to discover math principles and derive formulas themselves. Burke, an engineer, worried that his daughter wasn’t learning basic math skills.
“It was a lot of drawing pictures and playing games,” he said. “Her whole first-grade year was pretty much a lateral move.”
So for the past few years, Burke and his wife have been tutoring their three children after school — and this fall, they plan to switch them to North Beach Elementary, which uses a more traditional approach to math.

Sarah Natividad adds:

The biggest problem is that the teachers currently in service never learned enough math to begin with, and so can’t be expected to teach what they don’t already know. We only think our teachers know math because they know just as little math as we do. If you want to know how scarily ignorant of math our teachers are, I suggest reading Liping Ma’s Knowing and Teaching Elementary Mathematics for a start.
I’ve written about this on my own blog, and I’m not just talking out of my butt here. I’ve taught math to these potential teachers. They lack the prerequisite skills to pass a college algebra class. You can tell who in the class is in the Elementary Education program; they’re the ones sitting in the back row, getting a D on every exam because they have to use a calculator to do three times two (and they think this is normal). So when Bob Brandt of Bellevue says “How do you know three times two equals six? Any idiot knows that,” I would counter that an exceptional idiot must be teaching his kids math. We’ve raised an entire generation of teachers who don’t even know enough about math to know that they are ignorant of it.

D-Ed Reckoning touches on math as well.