Comment by antasvara

For what it's worth, that's how the Montessori school I went to worked. I have my critiques of the full Montessori approach (too long for a comment), but the thing that always made sense was mixed age and mixed speed classrooms.

The main ideas that I think should be adopted are:

1. A "lesson" doesn't need to take 45 minutes. Often, the next thing a kid will learn isn't some huge jump. It's applying what they already know to an expanded problem.

2. Some kids just don't need as much time with a concept. As long as you're consistently evaluating understanding, it doesn't really matter if everyone gets the same amount of teacher interaction.

3. Grade level should not be a speed limit; it also shouldn't be a minimum speed (at least as currently defined). I don't think it's necesarily a problem for a student to be doing "grade 5" math and "grade 2" reading as a 3rd grader. Growth isn't linear; having a multi-year view of what constitutes "on track" can allow students to stay with their peers while also learning at an appropriate pace for their skill level.

Some of this won't be feasible to implement at the public school level. I'm a realist in the sense that student to teacher ratios limit what's possible. But I think when every education solution has the same "everyone in a class goes the same speed" constraint, you end up with the same sets of problems.