What you already know determines what you can learn and how you think. Learning proceeds quietly and efficiently when what is new builds directly upon what is already secured. These ideas are among the most powerful messages emerging out of modern psychology. The effects of prior knowledge are dramatic yet well hidden from a teacher’s view. In this section we review the various types of knowledge your life experiences have provided for you. These types are summarised in Table 14.1. The first five types (sensory, strings, ideas, schemata, and mental models) can be collectively referred to as declarative knowledge, since they relate to knowledge that could potentially be expressed through words. On the other hand, procedural knowledge is indexed through actions.