In Russia we have such a system:
1) from 1,5 y.o. - nursery
2) from 3 y.o. - kindergarten
3) from 6-7 y.o. - school
3.1. elementary school - 1-3 grades
3.2. middle school - 4-9 grades
3.3. high school - 10-11 grades
Childrens must go to school till 9 grade. I mean if parents don't want to send them to school, police will come and ask parents uncomfortable questions)) Such parents could be deprived of parental rights. Into practice 99.999% have an education. Quite all of puples goes after 9 grade to college or after 11 grade to institute or university.
nursey and kindergarten are not obligatorily