I will send you the URL by email. Gredler, pages 71-76. One thing that can make constructivism difficult to grasp is that sometimes it seems like a philosophy, and sometimes it seems like a set of instructional practices. People may use these two senses of the word constructivism interchangeably, often without being clear about whether they mean one, the other, or both. As a philosophy, constructivism suggests that, while there is a real world out there, there is no meaning inherent in it.
Meaning is imposed by people and cultures.
This classification system is a human invention, and it is subject to revision or replacement. Thus, when we teach this classification system, we should teach it not as fact, but as the current system accepted by scientists. And we should also teach about the process of creating a classification system, not just the end product. Because it is my contention that you could be a constructivist in philosophy without always using constructivist teaching methods. However, we can continue to use Newtonian laws for many local situations because they work well enough and are simpler.