Where I went to school, 7th grade was in elementary school, and everyone took the same math. 8th grade was Algebra, Pre-Algebra, or "Remedial Math." I took Algrebra in a class of mostly 9th graders. A few years later, later, they decided that all the 8th graders should take it together because they were a little slower at first (due to lack of instruction) but were faster at the end. I remember not knowing certain terms (imaginary numbers, integers, real numbers, etc.) but not having any problems with the work.
My ds took Algebra as a 6th grader, without the benefit of pre-Algebra. I just couldn't see making him sit through another year of the same kind of math, and the school finally agreed. He really likes math and had learned a lot of math from the Murderous Maths books. He occasionally had a question for me about terms (ordinate, absissa, slope), but did well in the class.
