It's hard to believe but apparently true--despite the requirements of the No Child Left Behind Act, which so many educators poo-poo--that about 40% of poor and minority students are still taught by teachers who have neither a degree nor certification in mathematics.
I'd wonder how people could teach high school math without a degree or certification, but then I recall that I have no doubt I could teach several high school classes in which I don't have certification. I, however, would consider social science courses--history, government, geography--where it's not assumed that, as is so often the case, you either "get it, or you don't". Here in the US we assume that anyone can learn history, government, or geography, but only a chosen few can learn math. Maybe, though, there are people who are quite good at math and just didn't major in it or take a certification test--but they're fine teachers. I'm not here to say it can't happen.
I can definitely believe this, though:
The teaching problem is most acute in the middle grades, 5-8, the report said. That's a crucial time for math, said Ruth Neild, a research scientist at Johns Hopkins University.
In California, junior high teachers can teach with a "multiple subject", or elementary, credential. As such, they probably weren't the ones who took physics and calculus in college, although I'm painting with a very broad brush there. It's entirely possible that they're weak in fractions, decimals, and negative numbers--the very skills that are so vital, often in the same math problem, in Algebra 1.
Fortunately I've never encountered these almost-innumerate math teachers of 5th through 8th graders, but I'm sure they're out there.