The Clayton Christensen Institute for Disruptive Innovation, formerly the Innosight Institute, has published three papers describing the rise of K-12 blended learning--that is, formal education programs that combine online learning and brick-and-mortar schools. This fourth paper is the first to analyze blended learning through the lens of disruptive innovation theory to help people anticipate and plan for the likely effects of blended learning on the classrooms of today and schools of tomorrow. The paper includes the following sections: "Introduction to sustaining and disruptive innovation," "Theory of hybrids," "How to spot a hybrid," "Hybrid models of blended learning," "Seeing what's next with blended learning," and "Implications for education leaders." The report includes notes, a section about the institute, acknowledgements, and a section about the authors. [For "Classifying K-12 Blended Learning" (2012), seeED535180; and for "The Rise of K-12 Blended Learning: Profiles of Emerging Models (2011)," see ED535181.]