Teaching recorder to 3-4 CP has been a challenge since the third grades are starting with zero experience and some of the 4th graders are already on the 7th or 8th belt level. Today I had a very successful differentiation experience.
I had the 3rd graders watch this screencast from my webpage and follow along, writing in their music, while I talked to each 4th grader and got things straightened out as to which belt they should be on and what music they were supposed to be playing and which belt should be on their recorders. By the time I finished with my last 4th grade student, the 3rd grade video finished and we all had some time to practice in small groups or as individuals.
Fabulously effective. No time wasted. Perfect.