My son goes to a school with composite classes. One class is Reception / Year 1 and the other is Year 1 / Year 2. One thing I like about the school is that children of all different ages mix together.
It also seems to be very flexible in how they cater for the individual child. The tables can comprise of children of different ages. The Reception / Year 1 room has a pretty informal atmosphere. Which helps chidren like mine who are summer babies. They still do the appropriate year one work but still more of a fun atmosphere!
Some of the year ones are then slowly fed into the other room. It is pretty much Sept ones go first. Fairly sensible as Sept and summer babies are a more similar age to those above or below a year than each other!
Every term there is a class topic, like jungles, dinosaurs, where we live. So the children have group time to discuss then go to tables to work at their level. Even if a child is in the room for 2 years they won't repeat these topics.
My son is now in the Year 1 / Year 2 room and often joins the year 2's for science history sort of work but reading and maths is on a mainly year 1 table. It's nice that they can cater in this way.
I do wonder how a parent could take it if they saw other children the same age going up and theirs staying behind. I suppose it's how it's presented to the parents. The decision of what child goes where has much more to do with school intake numbers than who's brighter than who competition. Also to do with maturity, personality, listening ability etc
My son does have one very good friend who stayed in the reception / year one class. I know he's on the same reading books as my son but he's such a wriggle bum . Whilst he's a very capable young man he just needed to be in a more informal environment for a little longer. My son is also a wiggle bum and listening skills of a gnat but they decided he's react well to more being demanded of him in this way. Suppose that's children for you different methods work for different children.
Oh my I've waffled on. I think with many teaching/ school issues it's not what's done but how it's done.