Where i live, most children take Pre - School (which isn't mandatory) at the age of 3/4. Then the children go to elemantary school where they attend Kindergarten at 5/6 (depending on birthdays) and grades 1,2,3, and 4 follow that. The children then move onto a Middle School/Junior High at the age of 10/11 for grades 5, 6, 7, and 8. High School follows with grade 9, 10, 11, 12. By the time high school is over, they are about 17 or 18 - then they go to college for 2-4 years or more.
Our school system has us in school at 8 and has us leaving at 3. Between those hours, there are 8 periods (each period is a different class subject), each usually around 40 - 45 minutes long. When a student is a Sophmore (10th grade) then they can attened the Vo-tech (or Career Center); at the vo - tech you can take classes like Marketing, Electronics, Food Service, Automobile Repair, Protective Services, etc -- these classes are 3 periods in a row, and take up almost half of the school day. Also, in some of the Vo-Tech/Career Center class, you take take a work op in your Senior year (12th grade) where you go to school for a half a day to take your essential classes, then go to work the rest of the school day...and if you don't work that day, then you get to go home
When i went to a private elementary school, the only thing i noticed that was different from my school and the public elementary school was that the children in the private school had to wear uniforms and had to attend the 9 o clock church service during school hours every thursday. There was also class time where Religion was taught and discussed...too much

....I'm so glad i'm no longer in a private school

It's too constricting in private schools, in my opinion.