Identifying Teacher Practices that Support Students ’ Explanation in Science

Teacher practices are essential for supporting students in scientific inquiry practices, such as the construction of scientific explanations. In this study, we examine whether four different teacher instructional strategies, defining scientific explanation, making the rational of scientific explanation explicit, modeling scientific explanation, and connecting scientific explanations to everyday explanations, influence students’ ability to construct scientific explanations during a middle school chemistry unit. Thirteen teachers enacted the chemistry unit with 1197 seventh grade students. Approximately two weeks into the unit, the curriculum materials introduce scientific explanations and have students construct and revise their initial scientific explanation. We videotaped each teacher’s enactment of this focal and then coded the videotape for the four instructional strategies. We created a hierarchical linear regression model using these codes as well as students pre and posttest scores to examine the influence of these instructional strategies on student learning. We found that when a teacher discussed the rationale behind scientific explanation and modeled how to construct an explanation, that these instructional practices had a positive impact on student learning, while connecting scientific explanation to everyday explanation had a negative impact on student learning. The effect of defining scientific explanation depended on whether or not the teacher also discussed the rationale behind scientific explanation. If a teacher discussed the rationale behind explanation, defining explanation had a positive impact on student learning while if a teacher did not discuss the rationale behind scientific explanation, defining the components had a negative impact on student learning. Teacher Practices Supporting Explanation 2 Identifying Teacher Practices that Support Students’ Explanation in Science Classrooms are complex systems where many factors influence student learning including tools, teachers, and peers (Lampert, 2002). Recent research (Reiser et al., 2001) and reform documents (American Association for the Advancement of Science, 1993; National Research Council, 1996) argue that the role of the teacher is essential in structuring and guiding students’ understanding of scientific inquiry, a key learning goal in recent science education reform efforts. Teachers need to support students in making sense of these scientific practices (Driver, Asoko, Leach, Mortmer, & Scott, 1994). We are interested in how different teacher practices during the enactment of the same instructional unit influence students’ understanding of one specific scientific inquiry practice, the construction of scientific explanations. Role of Teachers in Inquiry It is not enough to acknowledge that teachers play a critical role. We need to know what their role is in order in order to help support teachers in the difficult task of creating an inquiryoriented classroom. Teachers have difficulty helping students with scientific inquiry practices such as asking thoughtful questions, designing experiments, and drawing conclusions from data (Marx, Blumenfeld, Krajcik & Soloway, 1997). Many science teachers may not have the appropriate expertise to create an inquiry-based learning environment (Krajcik, Mamlok, & Hug, 2001). Teachers need to learn new ways of teaching to promote scientific inquiry, which may differ from their own earlier socialization into school science as students (Lee, 2004; Metz, 2000) and their own orientations based on their experiences as students (Magnusson, Krajcik & Borko, 1999). Although teachers have difficulty supporting students in these practices, there is little research that provides guidance on what types of teacher practices may help students with scientific inquiry. Research literature about inquiry classrooms often does not describe the classroom practices, rather classroom inquiry is summarized as “doing science”, “hands-on science”, or “real-world science” (Crawford, 2000). Furthermore, researchers often label a classroom as inquiry-oriented based on the nature of the curriculum materials used by the teacher and not by what the teacher and students are actually doing (Flick, 1995). Since teachers’ beliefs about the nature of science, student learning, and the role of the teacher substantially affect their enactment of inquiry curriculum (Keys & Bryan, 2001), this raises the question of how using inquiry materials actually translates into inquiry-oriented classrooms. There is probably a range of inquiry occurring in these research studies labeled as exploring inquiry-oriented classrooms. Like other researchers (Flick, 2000; Keys & Bryan, 2001), we argue that there are few research studies that actually examine teachers’ practices in inquiry classrooms. Scientific Explanation One prominent scientific inquiry practice in both the standards documents (AAAS, 1993; NRC, 1996) and recent research literature in science education is the construction of scientific explanations or arguments (e.g. Bell & Linn, 2000; Driver, Newton & Osborne, 2000; JiménezAleixandre, Rodríguez, & Duschl, 2000; Kelley & Takao, 2002; Sandoval, 2003; Zohar & Nemet, 2002). Explanations refer to how or why a phenomenon occurs (Chin & Brown, 2000). An argument is an assertion with a justification (Kuhn, 1991) or a standpoint that is justified or defended for a particular audience (van Eemeren, et al., 1996). In our work, we use the word “explanation” to align with the national and state science standards that our teachers need to Teacher Practices Supporting Explanation 3 address, but our work builds off literature in both of these areas. Our goal is to help students construct scientific explanations about phenomena where they justify their claims using appropriate evidence and scientific principles. A key goal for science education is to help students seek evidence and reasons for the ideas or knowledge claims that we draw in science (Driver et. al., 2000). Engaging students in scientific explanation and argumentation is a fundamental aspect of scientific inquiry (Duschl & Osborne, 2002). Helping students engage in this practice may help shift their view of science away from science as a static set of facts to science as a social process where knowledge is constructed. Bell and Linn (2000) found that there is a correlation between students’ views about the nature of science and the arguments that they construct. They suggest that engaging students in this practice may help refine their image of science. Furthermore, engaging in scientific explanation may help students construct a deeper understanding of the content knowledge. For example, Zohar and Nemet (2002) found that students engaged in a unit on argumentation skills through dilemmas in human genetics, learned greater biological content knowledge than a comparison group who learned genetics in a more traditional manor. Although engaging in scientific explanation is an important learning goal for students, students often have difficulty articulating and defending their knowledge claims (Sadler, 2004). Kuhn (1991) investigated both children and adults’ ability to construct arguments and found that this practice often did not come naturally to them. They often had difficulty coordinating their claims and evidence. Even in a classroom setting where scientific explanation is an explicit goal, students still have many difficulties. Students can have difficulty using appropriate evidence (Sandoval, 2003) and providing sufficient evidence for their claims (Sandoval & Millwood, 2005). Students also have difficulty justifying why they chose their evidence to support their claims (Bell & Linn, 2000). In our previous work, we found that students had the most difficulty justifying why their evidence supports their claiming using appropriate scientific principles (McNeill et al., under review). We developed a scientific explanation framework for middle school teachers and students by adapting Toulmin’s model of argumentation (1958) to help support students in this difficult scientific inquiry practice. The explanation framework includes three components: a claim (a conclusion about a problem), evidence (data that supports the claim), and reasoning (a justification, built from scientific principles, for why the evidence supports the claim). In other work, we discuss the development of our framework as an instructional strategy (McNeill, et al., under review; Moje, et al., 2004) and as an assessment tool to examine student work (Lizotte, Harris, McNeill, Marx & Krajcik, 2003; McNeill & Krajcik, in press). In this paper, we are interested in exploring how teachers’ different uses of the explanation framework in their classrooms influenced student learning. Teacher Practices Supporting Scientific Explanation In terms of supporting students in the construction of scientific explanation or argument, there has been little research on teacher practices. Previous research on students’ construction of explanations in science has focused on scaffolds provided in the student materials or software program (e.g. Bell & Linn, 2000; Lee & Songer, 2004; Sandoval, 2003; Zembal-Saul, et al., 2002) or on students’ discussions in order to characterize their explanations (JiménezAleixandre, et al., 2000; Meyer & Woodruff, 1997). Tabak’s (2004) work has been some of the only research that has looked at the role of the teacher in helping students construct evidence based explanations. She argues that the teacher Teacher Practices Supporting Explanation 4 plays an important role in distributed scaffolding where many aspects of the learning environment, including software and other tools, come together synergistically to support student learning. Osborne and his colleagues (2004) have also recently begun exploring pedagogical practices that support students in argumentation. They argue that argumentation does not come naturally