Our school does segregate pretty well -- K-2 are in one hallway, and 3-5 are in another, and their recesses and lunches are at different times, so they really only run into each other on the way in and out of school. I'm not sure what the plan is for 6th if they include it with elementary. The new construction plans have changed a number of times, so I'm not clear on what's being built where.
MS/HS are in different parts of that building, with about the same setup, though some teachers have both MS and HS classes and there is some inevitable mixing there. Their lockers are in the different hallways, and lunches are staggered.
