CDT is an analytical framework to identify the components of the instructional strategies for different kinds of instructional goals. CDT describes instructional strategy in terms of strategy components: primary presentation forms (PPFs), secondary presentation forms (SFPs), and interdisplay relationships (IDRs).
The underlying principle of CDT is based on the assumption of Gagné Conditions of Learning, i.e. (1965, 1985) there are different kinds of learning outcomes and each of these different kinds of learning outcomes requires unique conditions for learning. CDT extended the outcome classification system by separating content type from performance level. The content and performance are two dimensions that are used to classify learning (TIP, 2001).
Image from Theory into Practice (TIP) database
CDT also added a more detailed taxonomy of presentation types and prescriptions for different kinds of learning outcomes. The prescribed conditions for learning are described in terms of different types of presentation, different types of practice, and different kinds of learner guidance. There are four primary presentation forms include: rules (expository presentation of a generality), examples (expository presentation of instances), recall (inquisitory generality) and practice (inquisitory instance). The secondary presentation forms include: prerequisites, objectives, helps, mnemonics, and feedback.
Merrill described a number of limitations of CDT (Merrill, Li, & Jones, 1991):
Gagné, R. M. (1965). The conditions of learning and theory of instruction ( 1st ed.). New York, NY: Holt, Rinehart & Winston.
Gagné, R. M. (1985). The conditions of learning and theory of instruction ( 4th ed.). New York, NY: Holt, Rinehart & Winston.
Merrill, M. D. (1983). Component Display Theory. In C. M. Reigeluth (Ed). Instructional-design theories and models: An overview of their current status, pp.279-333. Hillsdael, NJ: Lawrence Erlbaum Associates.
Merrill, M. D., Li, Z., & Jones, M. K. (1991). Second generation
instructional design (ID2). Educational Technology, 30(1), 7-11.