I’m not sure what the technical terms are, but at the moment, kids generally go from one grade to the next based on their age, and their ability only sometimes affects things causing them to go into special classes - though they’d usually graduate at the same time. Or if they’re held back, they’d be held back in all of the subjects…
I think it would better if school worked very similar to university, and kids wouldn’t be allowed to do subjects unless they’d passed the prerequisite subjects. They’d be able to redo subjects as many times as they want, but those who have a history of failing could be given extra help. The gifted kids would be able to pass all of the requirements for school quickly and that would be it - if the gifted kids want to do anything extra they’d do it elsewhere - at university or read books at the library, etc. Since you wouldn’t need extra stuff to stop gifted kids from getting bored at school then school could be cheaper.
In university style education they basically teach things once, then a group tutor can answer questions of a group and quiz them… and then there are exams. This allows material to be covered much more quickly. If kids learn intently the first time, they’re rewarded - they get to graduate quicker - or if they want to pace out the course, they have more free time.
There could be subjects where people in your age group get together - e.g. physical education - and the purpose could partly be for socialization between people of your own age group. But for most other subjects I don’t think it is necessary to only have people of the same age group in them - I mean at some schools they deliberately have some “home classes” where highschool kids of different ages are brought together - and there’s the rolecall, etc.
Anyway, the system I’m talking about guarantees that all graduates have fulfilled ALL of the requirements - I mean you could make it so that you can’t graduate unless you’ve passed a certain level of maths, english, etc.
I emailed the lady in charge of the state’s education system about this a while ago (I did a more formal and organized proposal) but she thinks things are fine the way they are.