I've talked about how our high school's math expectations drove out CMP in 7th and 8th grades. There was a curriculum gap for those kids who wanted to move into geometry in high school. The problem was clear and parents complained. I suppose our school could have put the top kids onto a pre-algebra/algebra track and left the lower kids in CMP, but they decided to use the same books and go at different speeds. This was probably for practical purposes, since the school only has one math teacher for 7th and 8th grades.
However, that's where everything stops. K-6 is driven by Everyday Math and the state's low requirements. The school looks at the number of kids who get to algebra in 8th grade and thinks that is perfectly normal. It's probably about the same number who made the top track in high school math as in the old "traditional math" days. (Is there any data on this?) The lower schools only focus on improving the relative scores of the state math test. It doesn't help that the scores at all of the other schools in the state stink. They only see a relative problem, not an absolute one. Everyday Math spirals along and assumes that kids will develop the necessary skills at their own speed. When 6th grade comes along and it doesn't happen, it's too late, so I assume they just point to the kids who did well. Of course, they never ask the parents of the good students what happens at home.
Do lower schools ever try to track kids longitudinally to see if any one particular teacher is a problem? Do they ever check to see if kids really do achieve a balance of understanding and skills; that they really are developing up to their potential? You would think that if they studied these problems, they would use teachers who were certified in math starting in first grade. Does anyone know of schools that send K-6 kids to a separate room/teacher for math? What math curriculum do they use? Do they separate kids by ability?
It seems to me that many of the problems kids have in math are caused by gaps and gaps are caused by "trusting the spiral". These problems can happen for both understandings and skills. Schools don't want to take the responsibility for ensuring anything but some state minimum on a statistical basis.