Primary school (Reception-Year 6): 4-11 years High/secondary school (Year 7-Year 11): 11-16 years College/sixth form (Year 12-13): 16-18 years University: 18-21 years, or longer depending on the course. A typical course is 3 years, but many study abroad for a year or do work experience. And, of course, many take a gap year and study later at 19/20/21 etc. Previously, people could leave full-time education at 16 and go on to work, or claim job seekers, but now 16-17 year olds have to be in education or training until their 18th birthday. Only applies to those born after 1 September 1997 though. What age you start and finish also depends on when you were born. I was born in late August, so I started full-time education literally about 3 weeks or so after my 4th birthday, and finished about a month before I turned 16.
There was a small change on the school system recently, but it's basically: Kindergarten: 3~6 (3 years) Fundamental Level: 6~15 (9 years) Middle Level (Highschool): 15~18 (3 years) Superior Level (College/University) would be after that.
Where I live in the East of England: Nursery: age 3-4 Primary/junior school (different schools have different names): age 4-11 High school: age 11-16 Sixth form college: age 16-18 (I have heard of some schools having built-in sixth forms, but none round here)
Preschool (younger than age 5) is completely optional. Elementary/primary school - Junior/ Senior kindergarten and 1-8 Highschool is 9-12
This was the closest to how it is, around here, including the being able to drop out at 16. Fun facts: If you tallied up my entire K-12 grade point average, I'd come out to either a very high D or a very low C. However, you tally up my test scores, I'd come out to a low A (Mathematics kills me), including our state appointed ones. Needless to say, this used to piss off instructors. I was also held back in the 7th grade, and it wasn't the grades that got me, it was the miss so many days = automatic failure. Between skipping and suspensions, it was bound to happen. Nobody asks why I was held back, they just assume it was due to bad grades.
Oooh this is interesting... In my country it goes like this: Kindergarten-preschool - (up to 7 yrs old) it is optional Elementary school - lasts 8 years, divided into first 4 years and the last 4 yrs (7 - 14 yrs old), obligatory High school - lasts 3, 4 (most schools are like this) or 5 years. (So, til' you're 18, then you get a bunch of exams to see where you can go next, if you chose a grammar school) - it was mandated obligatory somewhere around 3 years ago. After that, you can pause one year if you're planning to go to uni, or you can go right away next year. Or you can start working, naturally. Uni lasts depending on what you study. Other than that, the whole school system is highly inefficient.
In Quebec, it goes like this. Sometimes, students can be a year younger if they got in Kindergarden at 4 or older if they redid a grade. This is how old I was (or will be) at each stage and it basically holds true for my friends, too. Kindergarden (1 year): 5-6 Primary School (6 years): 6-12 Secondary School (5 years): 12-17 Cegep (2 or 3 years): 17-19 University: 19 + Let me say that I don't understand the school system in the US, also.
My school is very weird with this. k3-12 in one School. Preschool/Kindergarden/Day care is k3-k5 Elementary is 1-6 or k5-6 Middleschool (only so we can have a middleschool team) is 6-8 Junior High (What classes are labelled on the report cards, progress reports, and schedules) is 7-8 High school can be 6-12 (Middleschool and up), 7-12 (Junior high and up), 8-12 (when you can have classes mixed with grades 2 years older), or 9-12 (because other schools consider it that).
In my part of the US, you had to be 5 years old by September 1 in order to start Kindergarden. So grades went like this: Preschool (optional): usually ages 3-5 K - Grade 5 (elementary school): ages 5-11 Grades 6-8 (middle school): ages 11-14 Grades 9-12 (high school): ages 14-18 (my district divided this into 2 schools: grades 9-10 and 11-12, but this isn't normal) College/University (not mandatory): ages 18+ However, at grade 11 (age 16, usually), you could apply to a program to take college/university courses. I did this program, so I went to a nearby university for school at age 16. I had to take certain subjects to fulfill my high school requirements, but I could choose all of my other classes. At age 16, you were allowed to drop out of school, but this was strongly discouraged and often required extreme circumstances. There was also an alternate high school for students in grades 11-12 who needed a different learning environment. These students were often parents, had difficult home situations, or had some other circumstance which made the traditional school environment or schedule very difficult for them.
I go to school in Hong Kong Kindergarten - K1 to K3 we call it (ages 4-6, non-compulsory) Primary - P.1 to P.6 (ages 6-12, compulsory) Secondary - S.1 to S.6 (ages 12-18, compulsory) University (ages 18-22 or higher) But that's the main education system here, I know there are other schools that follow the IB system (which lasts from year 1 to year 13)