Everything old is new again: Schools rediscover the value of multiage classrooms: is.gd/IN32DH (Let's not forget that top-down, age-specific, test-driven standards helped to extinguish this beneficial practice)

I went to a K-12 school in Seattle (WA District #1). We had classes with up to 6 different grade levels represented. Sometimes everyone was taught the same material, sometimes the material was differentiated. That was in the 1980s. Have yet to find a reason NOT to do this.