Hi Mag,
My DS7 is in 3rd this year. Our school put him in a 4th grade math class last year where he completed the curriculum and pretty much the 5th grade curriculum too. They also put him on a computer program that our school uses (called successmaker through pearson). They didn't start it for him until almost the end of last year. They let him do this some during the 4th grade math class when they were repeating stuff he already knew, and during morning work time. He has almost completed the program though because it only goes up to 8th grade so not sure what they are going to do in terms of computer programs. They also let him do Khan academy some last year, but now he just does it at home some. But those were nice programs because they were about 20 minute sessions and you can stop when you are done. It doesn't seem to take much work for the teacher because they can put it on when other kids are doing morning work or something else that our kids don't need to do.
So this year they put DS7 in a 5th grade class for math. We may change this as the year goes on because he already knows all the material. The problem is the school only goes up to 5th grade and they didn't want to send him to middle school this year. So for now he goes to the 5th grade class, and then they let him do the 7th grade math on the computer. In the last couple years I sent in singapore math books and some other challenge math things and they let him work on those when the computer wasn't working or when something else unexpected happened. He also is on the 5th grade math olympiad team so that challenges him some. It's not completely perfect, but we are pretty happy with it so far. The also didn't want to use EPGY or any of that other stuff I suggested, but they were willing to use a program they already had for kids at school. And when I bought the program from home, the did let him use it some at school...but the loading took too long for some reason. Anyhow, I would check if your district has a computer program they already use.
good luck!
