A DNR perspective on mathematics curriculum and instruction

Guershon Harel has written an article called A DNR perspective on mathematics curriculum and instruction. Part II: with reference to teacher’s knowledge base, which was published online in ZDM on Tuesday this week. In this article, Harel touches upon many interesting issues concerning the teaching and learning of mathematics. Here is the abstract of the article:
Two questions are on the mind of many mathematics educators; namely: What is the mathematics that we should teach in school? and how should we teach it? This is the second in a series of two papers addressing these fundamental questions. The first paper (Harel, 2008a) focuses on the first question and this paper on the second. Collectively, the two papers articulate a pedagogical stance oriented within a theoretical framework called DNR-based instruction in mathematics. The relation of this paper to the topic of this Special Issue is that it defines the concept of teacher’s knowledge base and illustrates with authentic teaching episodes an approach to its development with mathematics teachers. This approach is entailed from DNR’s premises, concepts, and instructional principles, which are also discussed in this paper.