Question for British list members/school years

[Carol]

Geoff:
> Years 12/13 are not used as identifiers in the UK system.
> 
> We continue to use the old terminology so you will see schools 
referring to Lower Sixth/Upper Sixth or First Year Sixth/Second Year
Sixth.

Carol responds:
So a student goes from Year 11 to Lower Sixth? Isn't that a wee bit
confusing?

And are most students eighteen when they complete the Upper Sixth
(those with summer birthdays would still be seventeen)?

Geoff: 
> Just to cover some comments, the cut-off age date throughout the UK
is 31st August.

Carol:
Same here, at least in Arizona, but it used to be December 31.

Geoff: 
> Year 1 deals with the 5+ group - those who have reached 5 from the
1st September in the preceding up to the 31st August of the year in 
which they enter Year 1.

Carol:
So Year One corresponds to American kindergarten, not our first grade.

Geoff 
> So we tend to refer to Year 7 as the 11+ year. 

Carol responds:

Forgive me, but that's very confusing. It's all in what you're used
to, I suppose.

Geoff:
At one time - until the late 1960- all children changed from Junior
school to Secondary at this point. Now, it's a mix. Depending on the
area, the switch to Secondary can be Year 7, 8 or 9.

Carol responds:
I wonder whether the philosophy is the same as that in the U.S.:
youunger children and older children should be kept apart to prevent
bullying by older students.

When I was young, we had elementary schools, junior high schools, and
high schools. In Flagstaff, unusually, elementary school was
kindergarten through seventh grade, junior high was eighth and ninth
grades, and high school was tenth through twelfth. However, students
still graduated from eighth grade because that was the last year in
which all students were legally required to attend school. The ninth
graders called themselves "freshmen" as if they were in high school;
it was really only the fact that they shared a building with the
eighth graders (except for foreign language classes, which were in the
high school building next door) that made us junior high students.

Now many school districts have middle schools (generally sixth through
eighth grades) between elementary school (kindergarten through fifth
grades) and high school (ninth grade or freshman year through twelfth
grade or senior year). That system makes sense, I suppose. The oldest
elementary school students are only eleven year old--unless they've
been held back. The eleven through fourteen-year-olds (pre-teen and
early teen) are separate from everyone else, and the mid-teens to
older teens (fourteen through seventeen or eighteen) are together.
fifth graders now have a "promotion ceremony" to celebrate the end of
elementary school, but it's just a formality. And eighth grade
graduation is now also labeled a promotion ceremony, I suppose to
discourage fourteen-year-old are almost fourteen-year-old children
from thinking that they can now drop out of school.

Carol, describing the system as it was in Flagstaff in the old days
and as it is now in Tucson's two districts, but realizing that it
probably differs not only from state to state but from district to
district