A teacher is totally capable of teaching two separate math groups in one math period. Get one going work with the other get them going check in on group one. When I was a kid each teacher had two sometimes three reading groups and one big math group with the possibility of a small second math group. Just one kid advanced in math in a class might walk next door to a higher class, three or more needing acceleration stayed in class and became group two. I am sure there was a sub group of kids who needed extra tlc/instruction.
It isn't rocket science
