Content Knowledge is knowledge about the actual subject matter that is to be learned or taught, including, for example, middle school science, high school history, undergraduate art history, or graduate level astrophysics. Knowledge and the nature of inquiry differ greatly among content-areas and it is critically important that teachers understand this about the subject matter that they teach. As Shulman (1986) noted, this includes knowledge of concepts, theories, ideas, organizational frameworks, knowledge of evidence and proof, as well as established practices and approaches toward developing such knowledge. In the case of art appreciation, such knowledge would include knowledge of art history, famous paintings, sculptures, artists and their historical contexts, as well as knowledge of aesthetic and psychological theories for evaluating art.

Content knowledge is knowledge about the subject matter that is to be learned or taught, including, for example, middle school science, high school history, undergraduate art history, or graduate-level astrophysics. Knowledge and the nature of inquiry differ greatly among content areas, and it is critically important that teachers understand the disciplinary “habits of mind" appropriate to the subject matter that they teach. As Shulman (1986) noted, content includes knowledge of concepts, theories, ideas, organizational frameworks, methods of evidence and proof, as well as established practices and approaches toward developing such knowledge in a particular discipline. In the case of art appreciation, for example, such knowledge would include knowledge of art history, famous paintings, sculptures, the influence of artists’ historical and social contexts, as well as knowledge of aesthetic and psychological theories for understanding and evaluating art.

Pedagogical content knowledge (PCK) is the intersection and interaction of pedagogy and content knowledge. PCK is consistent with, and similar to Shulman’s (1986) conceptualization of teaching knowledge applicable to a specific content area. It covers knowledge of the core business of teaching, learning, curriculum, assessment and reporting, expressed, for example, in the conditions that promote learning and the links among curriculum, assessment and pedagogy. An awareness of students’ prior knowledge, alternative teaching strategies, common content-related misconceptions, how to forge links and connections among different content-based ideas, and the flexibility that comes from exploring alternative ways of looking at the same idea or problem, and more, are all expressions of pedagogical content knowledge, and are essential to effective teaching.

Pedagogical content knowledge is the intersection and interaction of pedagogy and content knowledge. PCK is consistent with and similar to Shulman’s (1986) conceptualization of teaching knowledge applicable to a specific content area. It covers essential knowledge of teaching and learning content-based curricula, as well as assessment and reporting of that learning. An awareness of students’ prior knowledge, alternative teaching strategies in a particular discipline, common content-related misconceptions, how to forge links and connections among different content-based ideas, and the flexibility that comes from exploring alternative ways of looking at the same idea or problem, and more, are all expressions of pedagogical content knowledge and are essential to effective teaching.

Pedagogical Knowledge is deep knowledge about the processes and practices or methods of teaching and learning, encompassing educational purposes, values, aims, and more. This is a generic form of knowledge that applies to student learning, classroom management, lesson plan development and implementation, and student evaluation. It includes knowledge about techniques or methods used in the classroom; the nature of the target audience; and strategies for evaluating student understanding. A teacher with deep pedagogical knowledge understands how students construct knowledge and acquire skills in differentiated ways, and how they develop habits of mind and dispositions toward learning. As such, pedagogical knowledge requires an understanding of cognitive, social and developmental theories of learning and how they apply to students in the classroom.

Pedagogical knowledge is deep knowledge about the processes and practices of teaching and learning, encompassing educational purposes, goals, values, strategies, and more. This is a generic form of knowledge that applies to student learning, classroom management, instructional planning and implementation, and student assessment. It includes knowledge about techniques or methods used in the classroom, the nature of the learners’ needs and preferences, and strategies for assessing student understanding. A teacher with deep pedagogical knowledge understands how students construct knowledge and acquire skills in differentiated ways, as well as how they develop habits of mind and dispositions toward learning. As such, pedagogical knowledge requires an understanding of cognitive, social, and developmental theories of learning and how they apply to students in the classroom.

Technological Content Knowledge (TCK) includes an understanding of the manner in which technology and content influence and constrain one another.

Technological content knowledge (TCK) includes an understanding of the manner in which technology and content influence and constrain one another. In planning for instruction, content and technology are often considered separately. It is assumed that developing content is what content experts do (i.e., historians develop history and physicists develop physics), whereas technologists develop technologies (e.g., hypertexts or overhead projectors) and technology integration strategies. When we think of subject matter that students study in school, we often do not think of curriculum content’s relationships to the digital and nondigital technologies that learners and teachers use. Historically, however, technology and knowledge have been deeply connected. New understandings in medicine, history, archeology, and physics have emerged, in part, from the development of new technologies that afford the representation and manipulation of information and ideas in novel and fruitful ways. Using new technologies (or existing technologies in new ways) can prompt fundamental changes in the nature of the disciplines themselves. Roentgen’s discovery of xrays, for example, changed both diagnostic processes and the nature of knowledge in medicine. The carbon-14 dating technique similarly revolutionized the field of archeology. Consider also how the advent of the digital computer changed the nature of physics and mathematics work, placing a greater emphasis upon the role of simulation in understanding phenomena.

Underlying truly meaningful and highly skilled teaching with technology, we argue, is Technological Pedagogical Content Knowledge (TPCK). TPCK is different from knowledge of all three concepts individually and in their individual intersections. It arises instead from multiple interactions among content, pedagogical, and technological knowledge. TPCK encompasses understanding the representations of concepts using technologies; pedagogical techniques that apply technologies in constructive ways to teach content in differentiated ways according to students’ learning needs; knowledge of what makes concepts difficult or easy to learn and how technology can help redress conceptual challenges; knowledge of students’ prior content-related understanding and epistemological assumptions; and knowledge of how technologies can be used to build on existing understanding to develop new epistemologies or strengthen old ones. TPCK is a form of knowledge that expert teachers bring into play any time they teach.

Underlying truly effective and highly skilled teaching with technology, we argue, is technological pedagogical content knowledge. TPACK is different from knowledge of its individual component concepts and their intersections. It arises instead from multiple interactions among content, pedagogical, technological, and contextual knowledge. TPACK encompasses understanding and communicating representations of concepts using technologies; pedagogical techniques that apply technologies appropriately to teach content in differentiated ways according to students’ learning needs; knowledge of what makes concepts difficult or easy to learn and how technology can help redress conceptual challenges; knowledge of students’ prior content-related understanding and epistemological assumptions, along with related technological expertise or lack thereof; and knowledge of how technologies can be used to build on existing understanding to help students develop new epistemologies or strengthen old ones. TPACK is a form of professional knowledge that technologically and pedagogically adept, curriculum-oriented teachers use when they teach.

Technological pedagogical knowledge is an understanding of how teaching and learning change when particular technologies are used. This includes knowing the pedagogical affordances and constraints of a range of technological tools as they relate to disciplinarily and developmentally appropriate pedagogical designs and strategies. It requires building a deeper understanding of the constraints and affordances of particular technologies and the educational contexts within which they function best.

Technological pedagogical knowledge is an understanding of how teaching and learning change when particular technologies are used. This includes knowing the pedagogical affordances and constraints of a range of technological tools and resources as they relate to disciplinarily and developmentally appropriate pedagogical designs and strategies. Developing TPK requires building an understanding of the potential benefits and limitations of particular technologies as they can be applied within particular types of learning activities, as well as the educational contexts within which these technologically supported activities function best.

Technology knowledge is always in a state of flux—more so than the other two “core” knowledge domains in the TPCK framework (content and pedagogical knowledge). This makes defining and acquiring it notoriously difficult. Technology is continually changing, and keeping up-to-date with technological developments can become a full-time job, in and of itself. This also means that any definition of technology knowledge is in danger of becoming outdated by the time this text has been edited, proofread and published. There are, however, certain ways of thinking about and working with technology that can apply to all technological tools. In that sense, our definition of TK is close to that of Fluency of Information Technology (FITness) as proposed by Committee on Information Technology Literacy of the National Research Council (NRC, 1999). They argue that FITness goes beyond traditional notions of computer literacy to require that persons understand information technology broadly enough to apply it productively at work and in their everyday lives. FITness therefore requires a deeper, more essential understanding and mastery of information technology for information processing, communication, and problem solving than does the traditional definition of computer literacy. This conceptualization of TK does not posit an "end state" but rather sees it developmentally--as evolving over a lifetime of generative, open-ended interactions with technology.

Technological knowledge is always in a state of flux - more so than content and pedagogical knowledge. This makes defining and acquiring it notoriously difficult. Keeping up to date with technological developments can easily become overwhelming to time-starved teachers. This also means that any definition of technology knowledge is in danger of becoming outdated by the time this text has been published. There are, however, ways of thinking about and working with technology that can apply to all technological tools, regardless of when they emerged. In that sense, our definition of TK is similar to the notion of Fluency of Information Technology (“FITness”) as proposed by the Committee on Information Technology Literacy of the National Research Council (NRC, 1999). The committee argues that FITness goes beyond traditional notions of computer literacy to require that people understand information technology broadly enough to apply it productively at work and in their everyday lives. FITness therefore requires a deeper, more essential understanding and mastery of technology for information processing, communication, and problem solving than does the traditional definition of computer literacy. Also, this conceptualization of TK does not posit an "end state," but rather assumes TK to be developmental, evolving over a lifetime of generative interactions with multiple technologies.