The school system in the US is rather different from other European countries.
Before 5, children can go to the nursery or Pre-school.
If your country provides a school for small children it can be interesting
to put them there or they can have an experience in an american "nursery".
The American system seems (according to expatriates) great for children. They've
got a lot of activities and they are free to participate, they spend a lot
of time outside playing (sport, drawing, construction...) and sometime they
meet inside for reading and discussion cicles.
The Pre-school is open form 7.30am to 6pm (the French
school for example in Berkeley closes at 3.30pm) 5 days
a week and 50 weeks per year (stop only 2 weeks at Christmas). Pre-Schools
and nurseries welcome also children below 2 in specific sections.
Prices are:
After age 5, all american children go to a Kindergarten
(sort of pre-elementary school). That class is usually in the school where you
want your children to carry on as it improves the chances to join that school
for the primary level (selection starts early here ;-).
As you might have noticed, schools in the US
are expensive, usually about $10,000/year for private schools (the French school
is $9000/year, but other bilingual schools can be $12,000)
Public secondary schools exist but their education is of variable quality.
The period of schooling goes from September till June.
Universities are also quite expensive . Private colleges have tuition of
more than $20,000 annually.