PROBLEM-SOLVING MODULES IN LARGE INTRODUCTORY BIOLOGY LECTURES ENHANCE STUDENT UNDERSTANDING.

A critical goal of introductory science courses is to develop students’ understanding of key concepts and principles. Typically, introductory biology courses include two major parts–lecture and laboratory. In tab, students have opportunities to engage firsthand in scientific inquiry. However, students are exposed to the bulk of the subject matter in the lecture setting. Problems with the lecture format are well known. Instructors tend to present large amounts of information, and students tend to transcribe, but not process, what the teachers tell them. In large classes, students are inhibited from asking questions, and it is difficult for the instructor to be attuned to what students actually learn. Even when lectures are well organized, students tend not to be engaged with the subject matter in ways that lead to understanding (McKeachie et al., 1986: Cooper & Robinson, 2000: Gardiner, 1994; Vernier & Dickson, 1967). An increasingly popular way to deal with these kinds of lecture problems is to use “‘active learning” strategies to get students more involved in the class (MacGregor, Cooper, Smith & Robinson. 2000). Students report they like the class experience better than straight lecture, and that active learning exercises help them maintain their attention better throughout the class period (Bligh, 2000). Active learning is a step in the right direction, but it does not guarantee that students will understand the subject matter. Students need to be more than active; they need to engage the subject matter in ways that lead to a deeper understanding of it. Research indicates that understanding is more likely to develop when students engage in activities such as analysis, evaluation, interpretation, prediction, and explanation (Bransford, Brown & Cocking, 1999; Coleman, 1998; Coleman, Rivkin & Brown, 1997). In biology, we want students to do the same kind of thinking that scientists do when they try to explain biological phenomena, such as interpreting data, making predictions, and explaining phenomena. These are “sense-making” activities through which students can develop deeper understanding of the subject matter (Perkins, 1998; Chi, deLeeuw, Chiu & LaVancher, 1994). We have designed problem-solving modules for introductory biology lectures in which students engage in this type of thinking. In a typical module, students are presented with a set of data about a biological phenomenon. They develop an explanation to account for the data, and then get feedback from the instructor about their explanations. In this study we examine the effects of a problem-solving module on student understanding of evolution and phylogenetic trees. In large lecture sections, students were presented with data about several animals and then worked in small groups to produce a phylogenetic tree to explain the data. The instructor collected and visually projected several of the models and analyzed them in front of the class. Instructor feedback focused on helping students develop their understanding of the concepts and revise any misconceptions of the material. This sequence was repeated two more times during the class period as students were presented with additional data. Assessment revealed that these in-class modules resulted in significant improvement in student understanding. Methods Course Background The module was tested during the fall 2003 semester in two different introductory biology courses, one for nonmajors (BIO 103) and one for majors (BIO 105). Both courses are designed for freshmen, have no pre-requisites, and course sections range in size from 40-150 students. These are traditional entry-level biology courses with sections on Ecology, Cells, Genetics, and finally Evolution. We tested the effectiveness of the module by assessing 577 students in six different lecture sections taught by five different instructors. Several of the lectures were videotaped and monitored by external reviewers.