My daughter is currently in a mixed age class, there are only 3 classes. She has always worked older children, but now she is in year 5 a lot of the children are younger than her. I remember thinking when she was 4/5 that I would like her to be accelerated, but now it doesn't seem to be the right fit. We may suggest flexi schooling as an option, the school seem to be open to this, if DD wants it.