This paper describes TPACK, technological pedagogical content knowledge (originally TPCK), a teacher knowledge framework for technology integration that builds on Lee S. Shulman's construct of pedagogical content knowledge to include technology knowledge. The paper begins with a brief introduction to the complex, ill-structured nature of teaching. The nature of technologies (both analog and digital) is considered, as well as how the inclusion of technology in pedagogy further complicates teaching. The TPACK framework is described in detail as a complex interaction among three bodies of knowledge: content, pedagogy, and technology. The interaction of these bodies of knowledge, both theoretically and in practice, produces the types of flexible knowledge needed to successfully integrate technology use into teaching.