Over the last decade, growth in K-12 online learning has exploded. Online enrollments--any instance of a student taking a half-semester course--have soared, and the total number of students taking online courses, either part time or full time, has climbed rapidly (Adkins, 2009; Picciano & Seaman, 2009; Watson, Gemin, Ryan, & Wicks, 2009). The growth has been so rapid in high school that in the book Disrupting Class, the authors project that by 2019, 50% of all high school courses will be online. Ambient Insight projects that by 2014, 10.5 million pre-K-12 students will attend classes online (Christensen, Horn, & Johnson, 2008; Adkins, 2009).
