tions” about physics, which made her pay more attention to those of her students. The research on students’ conceptions of science principles is substantial, addressing a wide range of scientific areas (Driver et al., 1985; 1994; Minstrell, 1989; 1992; Novak, 1987).

Research Finding 3: Students formulate new knowledge by modifying and refining their current concepts and by adding new concepts to what they already know (Driver et al., 1985; 1994). The research on conceptual change indicates that students change their ideas when they find these ideas to be unsatisfactory, that is, when their present ideas do not sufficiently describe or explain an event or observation. Further, they change their ideas when they discover alternatives that seem plausible and appear to be more useful (Hewson and Thorley, 1989). This is what happened with students in Ms. Flores’s elementary classroom as they considered why the trees grow differently, illustrated in Chapter 3, and Lillian’s college students, whose understanding of electrical circuits grew substantially as they were challenged with more complex phenomena, described in Chapter 5. Other research suggests that whether and how learners change their ideas depends on what they view as evidence for or against a competing idea (Duschl and Gitomer, 1991). This relates to students’ views of science and scientific explanations. Students often think of science as a collection of facts to be memorized and explanations as reports of isolated events. When this is true, there is less likelihood that students will actively

seek evidence for different explanations, think about why one set of evidence is stronger than another, and make good decisions about which explanation has the most support. Their ideas about natural phenomena are unlikely to change on the basis of sound scientific reasoning (Songer and Linn, 1991).

Research Finding 4: Learning is mediated by the social environment in which learners interact