I think that would only happen if you/re not very good at differentiation. All of my students had growth from the highest to the lowest.
I'm not saying there would be 0 growth. I just think the growth would be
higher if the class was tailored just for them. On an individual level, how could it not be? If the weaker students are not directly contributing to the growth of the stronger students, then they are at best neutral, and at worse hampering the progress of the stronger students.
So yes, everyone will improve. No dispute. But imagine you take the sum of growth of all students in the classroom. I'm not convinced that doing a purely mi mixed group would yield a higher sum than doing purely separate groups.
On the other hand, you could even mix it up, like switch classrooms around mid-day. Like first half of the day is all mixed, second half of the day some kids go to the gifted classes, others go to the remedial classes.
You already see this kind of thing in high school. AP courses. What if there were no AP courses, but you just tried to teach the material while all the weaker kids were in the same class? It wouldn't make much sense right?
