Laura, here is how I did it with a first/second grade class this year: Each weekend I read about four lessons from the first grade book and four lessons from the second grade book. Then I decided how to plug them in for each day of the upcoming week. The goal was to start one grade off on something they could do independently while I gave my attention to instructing the other grade. So, on Monday grade 2 might start by doing the game they had learned on Friday, or they might start with a Routine, like Today's Number. While they did that, I would do the lesson from grade one that required my full involvement with them. After they were off and going with something, I would check back in with grade 2 to just monitor, or to give some introductory instruction on what would be coming up tomorrow. Then on Tuesday grade 1 would be practicing or extending what I had done on Monday and grade 2 would work on something new with me. I would try to have one grade working at their desks, and another working down on the carpet with something, so they were physically separated from each other. I did a lot of bouncing back and forth. It does work, but you have to sometimes be willing to pick and choose through each lesson or switch lessons around or revisit activities with a grade, so that the system of "one grade doing something old, one grade doing something new" pans out. Good luck!