American school years

Hey I was just wondering, I'm from England and I always get really confused when people refer to like seventh grade and high school and stuff, could someone please tell me what all these are in american and australian and wherever its different lol .
here its primary school years 1 - 6.
year 6 = 10 years old
year 7 = secondary school first year, 11 years old
year 8 = 2nd year, 12
year 9 = 3rd year, 13
year 10 = 4th year, 14

and it just goes on like that...

Kindgergarten=usually 5 years old
1st
2cd
3rd
4th
5th
6th usually stars middle school
7th
8th
9th usually starts High School
10th
11th
12th usually 17/18 years old

^ Thats like the general idea....here in UT its a bit different i guess:

Elementary School
K: 5-6 years
1: 6-7 years
2: 7-8 years
3: 8-9 years
4: 9- 10 years
5: 10-11 years
6: 11-12 years

Junior High
7: 12-13 years
8: 13-14 years
9: 14-15 years

High School
10: 15-16 years
11: 16-17 years
12: 17-18 years

I notice that our system is different than most around us.....strange district Im in.

Man you guys have messed up scheduals.

Mine was the same as this one:

Kindgergarten=usually 5 years old
1st
2cd
3rd
4th
5th
6th usually stars middle school
7th
8th
9th usually starts High School
10th
11th
12th usually 17/18 years old

and for 9-12 they have special names.

9th- freshman
10th- sophomore
11th- junior
12th-senior

Thanks everyone!