USA school levels?

Question

So in Australia we have pre school, up until 4 years old, then we have primary school until you are 12 then high school until you are 18. 
How does it go in America I hear all this sophomore stuff, and does everyone go to collage over there? Is school not over until your 21? Curious?

Answer

High school is four years: 9, 10, 11 and 12. The sophomore stuff and such are nicknames for these grades and, to be honest, I have no clue why we say them lol.

9th grade - freshman 
10th grade -Sophomore 
11th grade -Junior 
12th grade - Senior

Most graduate at 18-19 (depending on when their birthday is), and can be held back until 21 years of age. Many Americans go to college but the drop out rate is large currently, usually contributed to personal financial issues.

USA school levels?

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