After moving toward this method of teaching last year I found that by saving as much time as possible during class for actual work I got to do way more quality teaching than I ever did in the past. Students were engaged and busy during class, and with me not wasting time preaching from the front of the room to a disinterested audience, I got to spend my time teaching students what they needed and wanted to know through a series of teachable moments with interested students. I love teachable moments, and I have found that the more time you have in class for one-on-one help, the more teachable moments you seem to have.
Next, students gain a lot of understanding through the video instruction. As opposed to a classroom lecture, students have the ability to pause me while taking notes and rewind to hear something again. In addition to this, they like the fact that they are watching a video instead of sitting still and shutting up. They've had enough of that, and my videos are different and therefore "cool."
I also go back to my college days and think of the lovely "Dale's Cone of Experience" and consider the implications of (a) using videos to present lecture content, (b) using class time for more active work, and (c) incorporating collaborative, project-based activities in class. I'm moving my class further down the cone by not having them "Read Section 2.4" or sit and listen to me preach.
Lastly, from a more practical and less theoretical viewpoint, I am teaching my students much more than just the Algebra I content expectations. They are picking up an invaluable life lesson in their taking ownership of their own education. They are learning a lot about knowing what they do and don't know as well as options they have to do something about it. They are learning, through the use of Khan Academy, that education is valuable and becoming increasingly more available and free for those who thirst for knowledge. And, they are learning to learn through the use of some 21st century tools that are becoming the norm in higher education.
I feel like I could ramble forever on this topic, and it is one that I love, but these are my big reasons for flipping my class. Hopefully my enthusiasm continues to rub off on my students as the year progresses out of the first marking period.
Image By Jeffrey Anderson [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons