At the beginning of the last unit, I sorted them by taking my top two students (grade-wise) and pairing them with the bottom two. Then for the next table, I took the next two best students and paired them with the next two lowest, and so on. The idea was that the better students would more drastically raise the game of those who struggled.
Today my students were working together on finishing up several things and the #1 table assigned one of the lower-performing students to explain their project to me after prepping him for the job. He gladly obliged. Later, when I came back around to check on them, I found that the two better students had created a couple of practice problems for the other two, who gladly did them, and corrected the problems later.
And they're freshmen.
Huge day for me...