For the uninitiated (or the uncredentialed), homogenized groups are where the teacher puts all the overachievers together in one group, all the middle kids in another group, and all the low kids in another group. Then, theoretically, you differentiate the work (translation: you give the overachievers all the hard real-world problems and give the low kids the basic, no frills easy stuff) so everyone learns at their own rate.
The problem with homogenized groups comes with the low achievers. These tend to be your ADHD kids, the ones that lose all focus the moment a fleck of dust floats past them. Have you ever seen what happens when you put all the ADHD kids at one table and tell them to work together? Turn your back on them for two minutes and it starts to look a lot like this.
Every year, the administration makes us try this. We split the groups up, homogenize them, and then give up after a few days. So what then? You stick the ADHD kid next to the overachiever. The overachiever threatens to kick the shit out of them if they don't shut up and everything's back to normal.