is so you can take Calc in 12th grade and not everyone is cut out for that. I think taking algebra in 8th grade is a little much for some kids, and just right for others.
10th - algebra 2
11th - trig/pre-calc
Most kids are not going to take the calc, but they need a math their senior year so as not to forget it all before college or post-voc training. They didn't offer algebra to 8th graders where I went to school and I had to take geometry and algebra 2 at the same time to be able to take calculus in 12th grade.