We use open enrollment for DS6 and he has used it at school a few times this year. But the school stated that the program was really slow for some reason both times he tried it though, so he hasn't really used it since since he spends all his time waiting for it to load. I think they are okay with him using it though. He doesn't really have much time to use it anyhow as he goes to another class for math, has math enrichment and math olympiads. I suggested they use it for reading too and ELA, but they gave him accelerated stuff for that now too. I do think it would be a good option though especially if you have a kid that can watch the little tutorial and plow on through.
Another good option for school is khan academy. My son does that at school some too. The school recently got him an account to use so he can do the exercises at home and school. He seems to like it and it moves quickly and is free.
