Another effective strategy for helping students overcome persistent erroneous
beliefs are interactive lecture demonstrations (Sokoloff and Thornton,
1997; Thornton and Sokoloff, 1997). This strategy, which has been used
very effectively in large introductory college physics classes, begins with an
introduction to a demonstration that the instructor is about to perform, such
as a collision between two air carts on an air track, one a stationary light
cart, the other a heavy cart moving toward the stationary cart. Each cart has
an electronic “force probe” connected to it which displays on a large screen
and in real-time the force acting on it during the collision. The teacher first
asks the students to discuss the situation with their neighbors and then
record a prediction as to whether one of the carts would exert a bigger force
on the other during impact or whether the carts would exert equal forces.