The third significant characteristic of the content of introductory mechanics
for considering conceptual change is that it is rich in what Mitchell and
Baird (1986) called "compelling situations." These are situations where the
competing views lead to very different and directly testable predictions about
what will occur. (The situations involving a pair of students on skateboards
in the sequence above is a good example.) However, there are other important
areas of science where there are far fewer compelling situations. This is
true, for example, for much of chemistry where the accepted scientific view,
such as a particulate view of matter, offers greater explanatory power than
the competing and common student view of matter as continuous through
being more consistent, more coherent, more parsimonious, and more detailed.
But a continuous view does not predict many different outcomes than
a particulate view. The characteristics of a better explanationmmore consistent,
coherent, parsimonious, detailed--are valued by scientists and teachers,
but not necessarily by students who can also assert "more abstract, more
complex, and more boring." Certainly as one studies more chemistry the
cohesive ideas of atoms and molecules do acquire very significant predictive
power, but, in the general science high school contexts we are considering,
compelling situations cannot be used in many content areas. In these
cases the second stage of the broad structure of our mechanics sequence