Haha its not that hard. Ok I will go through the schooling system with you
Primary school: 4 - 11 years
High school: 11 - 16 years
When your sixteen you take some exam called GCSE’s these are really important (or at the time they are) You have to get certain grades to get into six form where you study A-levels or a BTEC like I did.
So you then Graduate High school at 16 but if you stay on at sixth form you graduate again at 18.
Sixth form/college: 16 - 18 years
Basically sixth form is (excuse me if I am wrong) The final two years of American high school…Freshman and Senior year but you have to get through exams to get to those two last years.
Then the sixth form exams get you into university.
Hope this helps!