[gambiting]

>>Do you even have a child

I do. And like I said, you as a parent have a choice about the kind of school you send your child into. You don't have a choice whether they are in education or not.

>>And in general i don't see why any combination of ages should be a problem?

When you were at school were there many adult students in your classes?

>>you want another example in early years of Soviet Union there were 40 year olds learning to read with 6 year olds.

Yes, 100 years ago in the early days of the soviet union the classes were offered to everyone to increase literacy rates. I can assure you that throughout the rest of history of the soviet union you didn't have adults attending primary/secondary school, gymnasiums or other types of schools for children. Soviet union had schools for adults from very early on.