Though my DD's school is divided by age per class they do play with each other on the playground. What I've noticed with this setup is DD choosing to play with the older kids. Not shocking since she gravitates towards older kids in general. A common characteristic of HG+ kids. DD has a high empathy and is very mature for age. I believe this sets the groundwork for her acceptance of kids her age and getting along with them but also her ability to fit in with the older kids. She has no problem playing with kids in 3rd grade as well as kids that are age 3 but I definitely see the difference in how she interacts in each group.