So here in Australia we have:
- Primary School which goes from Grade Prep (a year before Grade 1) to Grade 6.
- Secondary School which goes from Year 7 to Year 12.
Year 11 and 12 are considered our 'senior' years and they were by far the most difficult (especially Year 12).
My University breaks the years down into two semesters (with mini Winter/Summer semesters between those). I just finished my 7th semester and that had an absurd workload, despite the fact that I actually took three classes instead of the usual four. My hardest semester was my 6th because there was a high workload, we had a family crisis during it, I got the flu during my exams and ended up with a 0 for one of the classes that I spent ages working (which I'll be repeating next semester).
So yeah...