Hi Lynn. This is the first year for about five years where I’ve actually had a discrete higher class and not a mixed class so I totally feel your pain on this one. I honestly think when SLT create these classes they have to accept that results are not going to be as good as when they have discrete classes.
I usually divided up the lessons so that I would introduce something new for one level toward the end of a period, so they could jump right in next period and I could do some teaching with the other lot. It’s not ideal, and there’s always someone off.
I don’t have any silver bullets for you but I wish I did!