Whatever he chooses, it is for proper abstraction of mathematical concept and the students will benefit from it. The students will understand the concept through representations of the materials and interactions with the material. So it is possible that the teacher's strategy will turn out to be effective. The more important thing is that the teacher should be able to think about strategies in students' place because a strategy that the teacher thinks as the best is not necessarily the best one for the students. He told that people continually try to understand and think about the new in terms of what they already know.
Students are the same in learning and understanding of mathematics.
In deciding a strategy, my experience as a foreign student in the United States provides an important idea. The social and cultural factors should play a role in deciding a strategy in a country like America where the diversity is common to everything. In the above example, if I were a student who are supposed to learn the place value with American monetary system by my teacher the material would not provide me any significant information that I have to obtain from the material. The multibase arithmetic blocks will be more useful to me because of their difference in quantity while the bills which have no physical difference will be more effective to most of American students because of a familiarity to the monetary system in the society for a long time. The second issue is teaching mathematics with knowledge about the results of educational researches.