teaching. The article argues that the coarse separation of "teachers' subject matter knowledge" and "formal disciplinary knowledge" is inherently problematic. Rather, they argue that mathematics-for-teaching is likely neither a matter of "more of" nor "to a greater depth than" of an in-service session, but rather a "branch of mathematics". They use classroom multiplication to illustrate four categories of elements involved in teachers’ mathematics-for-teaching, namely, “mathematical objects,” “curriculum structures,” “classroom collectivity,” and “subjective understanding”.
1. In the discussion of teaching multiplication, the authors assert that the understanding multiplication is not about how many figurative aspects of multiplication are taught but physical actions out of which multiplication arises. First of all, if this is the sudden conclusion of 24 experienced teachers after lengthy discussion of teaching multiplication in classroom, I would be disappointed at the quality of the mathematics courses which qualify those teachers. Strangely, I have to agree with the authors that we do need a special "branch of mathematics" for math teachers.
2. I found that the following illustration in the article was very intriguing especially when I realized that the stem splits to symmetrical halves: stable knowledge and dynamic knowledge.
Question: Compared to mathematicians, math teachers' expertise lies in the fact that their math is done through interactions with others. Should we value more their knowledge or their ability to engage students in meaningful discussion?
