material is introduced. Use questions and discussion to probe for additional misconceptions. Students will often surprise you with the variety of their preconceptions, so be careful to listen closely to their answers and explanations. You can help students by asking them to give evidence to support their explanations and by revisiting difficult or misunderstood concepts after a few days or weeks. Misconceptions are often deeply held, largely unexplained, and sometimes strongly defended. To be effective, a science teacher should not underestimate the importance and the persistence of these barriers to true understanding. Confronting them is difficult for the student and the teacher.
Some misconceptions can be uncovered by asking students to sketch or describe some object or phenomenon. For example, one might ask students to sketch an atom before doing so on the board. Even students who have a strong high school background might show a small nucleus surrounded by many electrons circling in discrete orbital paths, much like the solar system. By asking them to draw their own model first and then asking some students to share their answers with the class, a teacher can identify preexisting models and use them to show the need for new models.
Example of a Conceptual Misunderstanding
Students were asked to sketch the air in a sealed flask initially and after half of the air was removed. In this study, fifteen percent of college chemistry students sketched the second flask with regions containing air and other regions containing empty space (Benson et al., 1993).
Strategies for helping students to overcome their misconceptions are based on research about how we learn (Arons, 1990; Minstrell, 1989). The key to success is ensuring that students are constructing or reconstructing a correct framework for their new knowledge. One way of establishing this framework is to have students create "concept maps," an approach pioneered by Novak and Gowin (1984). With this technique, students learn to visualize a group of concepts and their interrelationships. Boxes containing nouns (and sometimes adjectives) are connected to related terms with a series of lines; prepositions or verbs are superimposed on the connecting lines to help clarify the relationship. A sample concept map is shown in Figure 4.1 While some studies indicate that concept maps do not enhance meaningful learning in biology (Lehman et al., 1985), others have obtained the opposite result (Okebukola and Jegede, 1988). Esiobu and Soyibo (1995) reported that students constructing concept maps in cooperative groups show a greater increase in conceptual learning than students working individually, thus the utility of concept mapping may depend on the instructional setting. Similar results were obtained by Basili and Sanford (1991), who found that cooperative group work on concept-focused tasks had a significant effect in helping college students overcome certain misconceptions in chemistry, even though it did not involve concept maps.
Using Demonstrations to Help Students Overcome Misconceptions
Carefully selected demonstrations are one way of helping students overcome misconceptions, and there are a variety of resources available (Katz, 1991). In the example of a conceptual misunderstanding about gas volume cited in an earlier sidebar, the authors suggest that a demonstration using a colored gas could be very effective in showing students that the gas fills its container.
Helping students to reconstruct their conceptual frame work is a difficult task, and it necessarily takes time away from other activities in a science course. However, if you decide to make the effort to help students overcome their misconceptions you might try the following methods: