They should eventually be able to form groups...and work as peers. Is there really a difference between a 12y/o and a 13y/o...as adults, we don’t always consort with those born within the same solar year. Why wouldn’t it work for kids?
> Is there really a difference between a 12y/o and a 13y/o
There can be huge differences in social development there, and not even strictly tied to age. The variance is rather large.
But even if you just look at averages, as far as I can tell the average 13 y/o girl and the average 12 y/o boy are quite far apart in terms of their social interactions, starting with basics like "are you thinking about dating yet?"
All that said, getting 12- and 13- year olds to work as peers is a much simpler problem than the originally posed one of getting 5- and 10- year olds to work as peers. In _that_ context there are a bunch of problems, ranging from difference in attention spans to the basic issue that most 5-year-olds don't know how to read yet, and most 10-year-olds do, and so conveying information to both together in a way that's not frustrating to one or the other can be quite difficulty.
Now if we want to group students by ability (5-year-old who can read, great, let them work with that 8-year-old if they have an interest in common) instead of age, that might work much better than any sort of age-based grouping. Of course that can exacerbate the social aspects, but there are in fact ways of making this work well. Having the older student partially teach the younger one, for example, is a good way for the older student to significantly improver their own understanding of the material.
Maybe they should learn a diverse group of children. Girls and boys are ‘different’ but we don’t segregate them anymore...why should we segregate them on the basis of one year age gap?
Except all the places we do (single-gender schools do exist, and even in non-single-gender schools physical education and health are often taught separately).
Also, maybe we should do more of this; there is some evidence in the literature that at some ages educational outcomes would be better with gender segregation if we did things right in terms of keeping equality of resources. Which is of course the sticking point.
> why should we segregate them on the basis of one year age gap
In case it wasn't clear from my answer above, I don't think we should. I think we should group kids by interests and current level (i.e. by what they will be trying to learn) a lot more than we do now.
I am saying that there are some studies showing gender segregation at certain ages may improve educational outcomes, largely depending on how it affects teacher behavior. Whether that means we should do it rather depends on whether we can get those teacher behavior effects in other ways and whether gender segregation would cause other issues (e.g. unequal resource allocation).
For some specifics that are pretty easy to find, see http://econweb.umd.edu/~turner/Lee_Turner_Gender.pdf for recent evidence that boys do may do better in all-boy schools, at least in some cultural contexts. There were a bunch of studies in the '90s that claimed girls do better with no boys in the class, due to teachers actually noticing them, but that effect seems to have more or less disappeared over the last 20-25 years.
In general, as in all things to do with kids and education the answer is almost certainly "it depends". Some children do better in a gender-segregated environment. Some do better in a gender-integrated one. Some don't particularly care. Hence all the caveats above about "some" and "may" and so forth. The hard part is figuring out when gender-segregated education is appropriate and when it's harmful, on a student-by-student basis. Unfortunately, public education is too cookie-cutter for such details.
5 year age difference may be a bit much but beyond that, montessori is doing exactly that. they group children in ranges of 3 years: 0-3,3-6,6-9,9-12,12-15,15-18