Lets do a little math
The school year runs for 40 weeks, give or take depending on where you are in the world.
Forty multiplied by 5 equals 200 days in the school year, minus a few days off for public holidays, etc.
200 multiplied by, lets say 5 hours of actual class time each day, equals 1000 hours of learning every year.
Thats a lot of hours.
School exams are usually 3 hours long.
Do you get where Im heading with this?
1000 hours of learning time squished into 3 hours of exam time.
This is why students who give equal weight to everything theyve learned that year when they study dont get the grades their effort deserves.