Kurzer Text bitte korrigieren (Englisch)

Wäre sehr nett, wenn mir jemand, dass korrigieren könnte, ich muss über High schools eine Präsentation halten.

In the USA the students changed after Elementary school to Middle school .
After that they attend the actual high school , wich is also called senior high school or Senior high. The construction of schools is diffrent from school district to school district . In some states the students have to go to high school until they are 18. The traditional construction for high schools is from 9 th to 12 th grade. In other states they are allowed to leaving s chool with 16 or 17 if the parents allowed . In senior high school , the classes are not only marked with numbers , the students of the individual classes also caryy special names , The 9 th Graders are called " freshmen ". The 10 th Graders " sophomore ", the students from the 11 th Grade are " j uniors " and the 12 th Graders are called " seniors ". The same titles are also used in colleges and universities .