Which is almost exactly what high school is in some parts of the US (that is, in places where it is 10-12 grade.)

The thing is, while the US tends to have the Elementary/Middle or Junior High/(Senior) High split in most places, the grade levels aren't the same.

I've seen (and this may not be exhaustive) the splits with the following grade levels:

1-5/6-8/9-12

1-6/7-8/9-12

1-6/7-9/10-12