| Chemistry is a conceptually difficult subject for many high school students. Upon completing introductory chemistry courses, many students leave with substantial misunderstandings about chemical processes, chemical systems, and even the nature of matter itself (Krajcik, 1991). One problem for students in understanding chemistry lies in making the connection between observable, macroscopic level phenomena and the unobservable, underlying mechanisms at the molecular level.; A potential solution to this problem is to encourage students to actively generate and use scientific representations to help them make connections between the macroscopic and molecular levels. Literature on students' use of representations points to the importance of representations for chemical understanding. In particular, research shows a positive correlation between the active creation and discussion of chemical representations and increased learning.; This study compared student learning associated with the creation versus selection of representations. In particular, this study investigated the use of a National Science Foundation funded, representation-based computer learning environment for conceptual change in chemistry called the ChemSense. The hypothesis of this study was that students who actively created chemical representations would outperform students who selected expert-generated representations as indicated on test, interview, and presentation measures.; To investigate this "create" versus "select" hypothesis, a one-month study involving seventy-eight students in three Northern California high school chemistry classes was designed. Two experimental treatments---"create" representations and "select" representations---and a third, quasi-experimental group that had a combination of the two experimental treatments were studied. Repeated test and interview measures, as well as student presentations were used to identify differences between treatment groups.; Analysis of test, interview, and presentation measures revealed no significant differences between the create, select, or combination treatment groups. The findings did not support the hypothesis that students in the create condition would outperform students in the select condition. In all cases where a repeated measures indicator was used significant differences between occasions were found. Although the findings do not favor a particular treatment condition, some measurement artifacts such as drawings generated during student interviews are encouraging and suggest that ChemSense may be an effective tool for student generation and discussion of representations. |
