Interesting; I spent all but one year of pre-highschool education in montessori, and the groups were

- pre-k + kindergarten - grades 1-3 - grades 4-6 - grades 7-8

I can see how moving 1st grade into the first bucket would help even things out. I think pre-K was often 2 years, though, so the first bucket still covered 3 ages or grade-levels.