One defining feature of the concentric method in teaching is its temporality. According to education theorist John Field, it has been shown that learning occurs best when the lesson is delivered over time, at regular intervals. This is why, for example, teachers often repeat key terms once or twice a week for the duration of a unit. In concentric teaching, temporal repetition occurs as the student goes deeper into a subject. As the student reaches a new depth of understanding in math, for example, the teacher might re-introduce a topic that was initially introduced in an earlier level, and explain how this concept still applies at the deeper level.
Conditioning is a crucial component of the education process. Conditioning occurs when a learned behavior is reinforced, either through repetition (practice) or incentives (being rewarded for behavior). Classical conditioning occurs when you associate a stimulous with a reward (e.g. dogs learning to salivate at the dinner bell), whereas operant conditioning occurs when you associate a behavior with a reward (e.g. memorizing an escape route). The concentric method uses operant conditioning, as it involves getting students to repeat their knowledge at different levels in the curriculum, thus emphasizing the effectiveness of the original lessons.
In the concentric method, curriculum proceeds from shallow to deep. In early math lessons, for example, a teacher might emphasize methods of solving equations, then move into the rationale behind these methods as the lessons progress. The reason for this is simple: it is easier to learn simple methods than it is to learn complex philosophical principles, and most of the time, learning techniques early on helps you later on when you try to learn theory.
The concentric method moves from narrow to broad as the curriculum progresses. At first glance, this may appear to contradict the fact that concentric teaching moves from shallow to deep, since it is hard to know a broad range of topics at a deep level. This tension can be reconciled by the fact that the concentric method emphasizes constant repetition. As the student moves in deeper in a broader range of subject, the teacher constantly emphasizes the basic principles learned in the early lessons, so the deep principles and the broad topics are both tied into the basic material in a straightforward way. The repetition solidifies the material in the learner's mind.