A wildly successful "flipped" classroom experience

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.

Why I Do This

Its been a tumultuous year for me at Countryside. Our switch to rotating through music every 4 days instead of twice a week has me way behind on teaching standards and curriculum. I am struggling to provide the same quality of music education just because my quantity has been reduced and I simply can't offer the same depth.

This is my first year of teaching 3/4 and 5 Continuous Progress and I am loving it. It's fun to build relationships with these students but I've been feeling sad that they are not getting a "real" Mrs. Prowell experience because of the reduction and I'm having to take extra long on certain concepts (just because they forget so much over the course of a week) while completely skipping over others. It has been a very frustrating experience. 

Then I get this letter today: 

"Dear Mrs. Prowell,

 I hope you have had a great holiday season I really enjoy the music room because you always have something fun planned for us to sing. You don't just have one day for us to show our musical talent but you make that every day. You have grown my passion for music and you show that you can do anything you want with music. I really enjoy your positive attitude you always have and you make the room just perfect for all of our education.

Sincerely, [I'm leaving this 5th grade student's name off the blog]"

Wow.