Five years ago, a pair of science teachers at Woodland Park (Colorado) High School turned their pedagogical approach upside down. Rather than stand up in front of the classroom, they sent their respective students home with videos of themselves lecturing. And rather than assigning traditional homework, work that most students could get tripped up on if they are not sure about a certain topic, the teachers gave students time in class--with their close supervision and help--to put their learning into practice. Although it is hardly in mainstream use, the concept of "flipped learning" has spread considerably during the past five years throughout K12 education. It's unknown how many schools or teachers use flipped learning now, but one measure of its recent growth is the explosive upsurge of users--from 2,500 to 9,000 since January--on the Ning social media site of the Flipped Learning Network, a national clearinghouse on the teaching methodology. Educators say that flipped learning can greatly increase a teacher's ability to provide differentiated instruction given that students work at their own pace in the classroom--and teachers can provide more challenging work for those who are breezing through. Students--including special education students--having difficulty with concepts can pause and rewind the videos to give themselves extra time to parse out what a teacher means. That is one of the most powerful things about these videos: that students who process slower, can process slower. Slower learners can be afraid to interrupt a teacher in a lecture, for fear of being seen as less intelligent while brighter students quickly become bored. The flipped classroom also can help ELLs, especially since the videos can be equipped with closed-captioning so they can see and hear the English at once--and for the hearing impaired. The teacher who no longer necessarily has primary responsibility on lecturing about how to do math on that particular day, can also do much more powerful things with individual students, with regard to understanding where the roadblocks are happening, as they are happening. (Contains 5 online resources.)