Or just...not have students at wildly different levels in the same class. At high school and more so in universities, there are distinct classes at different l

Or just...not have students at wildly different levels in the same class. At high school and more so in universities, there are distinct classes at different levels, and prerequisites for those classes, and students at different levels. Bring that system to all grades, rather than just having "age N = grade X" as one giant class with pressure for uniformity.