We have no evidence that larger enrollment is better for learning. In fact, larger classes suggest that students might get less attention, which could make it harder for children to learn.

This is something negative about today’s mixed-age classrooms compared to the past. So, it’s not going to help explain why mixed-age classrooms today achieve better results.

This is something positive about today’s mixed-age classes compared to the past. More engaging projects might lead to less boredom for older students and more attention given to younger students. This is the only answer that says something remotely positive about today’s classes.

We don’t know whether having a greater range of ages is a positive development for learning. There’s evidence it isn’t, because past results show older students were bored, and younger students were confused. Increasing the age disparity in class might hurt learning.

This says most teachers of mixed-age classes today are not students in mixed-age classes when they were young. This doesn’t tell me something positive about mixed-age classrooms today compared to the past.