How long do you spend in school?

Working on UK system...

Assuming you're just talking about mainstream education starting at age 5 and leaving at age 16...

11 years = 4018 days. Subtract weekends (4018 - 1144 days), leaving 2874 days.

Subtract main holidays... (2874-77 days) equals 2797 days - which is a little over 7.5 years.