The authors open this article with a description of an incident that happened in 1992, when 28,800 rubber bath toys (i.e., ducks, frogs, turtles, and beavers) fell off a cargo ship in the middle of the Pacific Ocean. In 2009, these rubber bath toys were still washing ashore on beaches all around the world. This science instruction can be used with…

This article argues that an important source of the difficulties posed by particular concepts and theories is the narrow range of "types of causal models" with which most learners are familiar. Most learners are familiar with relatively simple styles of causal models, but many concepts and theories in science depend on styles…