else-2003sdt

This study is a formative evaluation of analogies as one of multiple tools used to help middle-school students understand cellular respiration and the body systems associated with it. In a curriculum trial that was conducted in three schools, analogies were used to help students develop understandings in areas that may be inaccessible through student reasoning, prior knowledge, or direct experience. We propose that students may process and understand analogies differently based on features of the analogy such as familiarity of the base, complexity (number of mappable elements) of the analogy, goal of the analogy (to illustrate structural or functional features), "nearness" or "farness" of the analogy, and position of the analogy in the instructional sequence. We explore evidence that there are different types of "pitfalls" in analogies based upon the criteria above using evidence from our trials, and suggest curriculum revisions and teaching methods that may help address these difficulties.