Is it okay to write this way in the FORMAL writing?

"What is good about schools in Japan is that children from different classes all study at the same school. "

I thought the word "all" should be written like "all children from different classes ...", but is it perfectly ok to put all in between classes and study?
If so, what's the difference between them?

Bir çeviriye bakın

Do not start the sentence with what. In formal writing it's incorrect. Rather write, " The good thing about schools in Japan is..."
It sounds more correct to put 'all' between classes and study. When 'all' is used before children, the meaning changes a little bit. It sounds like every child in Japan is studying in school or is having access to education. When you use all between classes and study, it sounds like despite being from different classes all children study in one school ie one school accommodates different classes of students.