CROSS CASE ANALYSIS, DISCUSSION AND CONCLUSION
I employed a multiple case study approach to identify how Knowledge of
Scientific Models (KSM), understanding the Nature of Science (NOS), and the ability to use questioning to facilitate Model-Based Teaching (MBT), influenced three teachers’ ability to implement MBT. In this chapter, I will first describe the similarities and differences among the three cases with regard to the three characteristics described above. I will also describe the similarities and differences of each teacher’s growth network as described by the Interconnected Model of Professional Growth (IMPG) (Clarke & Hollingsworth, 2002). I will then describe how I used these similarities and differences to generate a performance progression of Model-Based Teaching
implementation. Limitations of this study and Implications for professional development providers will also be discussed.
Knowledge of Scientific Models and Scientific Modeling
In all three cases, each teacher possessed an uninformed level of KSM prior to attending the summer professional development institute. While they recognized that Scientific Models should be used in the classroom, they were doing so in unsophisticated ways. For example, in her pre-institute lesson video, Laurel described models as
molecular structure. She made no explicit differentiations between the models and the molecules nor did she connect the models to a purpose or identify them as a product of science more generally. These three teachers did not engage students in explicit
discussions about the nature of the model itself nor about why one model might be more useful than another. Although they described using different types of models, the purpose of the model was to facilitate student understanding of a curricular topic. While these activities utilized the descriptive and explanatory abilities of models, these teachers were not using them in ways that were similar to how scientists might use models as
investigatory or predictive tools.
While using the Interconnected Model for Professional Growth (IMPG) as an analysis tool, I determined that each of the three case study teacher’s growth networks began with the professional development institute which was situated within the External Domain of Clarke and Hollingsworth’s (2002) model. The PD instigated enactments and reflections on both the Personal Domain and the Domain of Practice for each teacher. While institute activities were intentionally structured to engage teachers in developing and enacting modeling lessons, these three teachers also enacted new lessons in their classrooms in the subsequent school year. The teachers reflected on these classroom enactments in different ways, but the fact that they did engage in developing model-based lessons indicates that participation in the model-based lesson development at the summer institute was effective in getting these teachers to consider scientific models in more explicit and sophisticated ways.
explicit discussions about the purpose of models and their role in science were being included in the introductory discussions that often take place at the beginning of a school year. For example, Andy began his school year by adding a lesson on models following his discussion of “The Scientific Method”, Carla was adapting elements of the modeling pedagogy throughout her teaching, and Laurel was persistently practicing her facilitation of whole class discussions using whiteboards on which students had drawn diagrammatic representations of their understanding. For these three teachers, scientific models had taken on a new importance as evident by the increased prominence of models in their teaching.
Use of Questioning to Facilitate Modeling Discourse
There were more similarities than differences between each teacher’s growth in knowledge of scientific models over the course of this study. Both before and after the professional development institute, there were more differences between the three teachers use of questioning than similarities.. Through the process of identifying and describing these differences and analyzing each teacher’s growth using the IMPG, I began to recognize that Andy was quite different from both Carla and Laurel.
Andy’s use of questioning was embedded within a didactic, traditional style of teaching and primarily used a initiate-respond-evaluate cycle of discourse known as Triadic Dialogue (Lemke, 1990). During the practice teaching activities of the
institute, Andy did attempt some of the more ambitious questioning strategies that were discussed and demonstrated as part of the institute. However, these strategies were not present during the classroom observations.
Carla was quite different from Andy with regard to questioning. Carla employed a variety of questioning strategies both before and after the summer institute. Her pre- institute video showed her asking open-ended questions and probing student responses. Some of her interactions could be described as an IRE pattern. Yet, open-ended questions and less evaluative responses were more evident in her classroom dialogue than in
Andy’s. In her post institute classroom observation, Carla rarely engaged in an IRE pattern. She had expanded her repertoire of questioning strategies to include the reflective toss and asked students to re-voice each other’s ideas as she checked for understanding. She was visibly hesitant to evaluate student responses and she was making her efforts to be metacognitive explicit to her students.
Laurel was not quite as skilled with using questions to facilitate classroom
discussions prior to the institute. She referred to the activities of the summer institute that focused on questioning and discourse as the most meaningful activities of the institute. She referred to her questioning abilities as a “hole in her teaching”. During the practice lessons, Laurel made an effort to practice all of the strategies that had been discussed by the institute instructors. In a post institute interview, Laurel linked her efforts to improve her questioning skills to her intrinsic interest in maintaining a student centered classroom in which students were forced to think and make sense of the content.
While Laurel and Carla began at different levels of ability with regard to
questioning, Laurel’s persistent efforts to improve and Carla’s adoption of new strategies into her repetoire differentiate them from Andy in a meaningful way. This is evident
either originating or developing, is the Personal Domain. For Laurel and Carla, this is not the case. The enactions and reflections in Carla’s growth network are primarily coming from the Domain of Practice. Laurel’s are coming primarily from the Domain of Consequence. This indicates that Laurel and Carla are primarily concerned with
classroom impact whereas Andy is more focused on his own learning and position in the classroom. Laurel and Carla’s focus on student ideas and classroom practice were integral components of their implementation of MBT.
Understanding the Nature of Science
In Part 1 of this study, each teacher’s level of understanding of the Nature of science was determined through the use of two instruments, the VOSE and the VNOS-C. I determined that both Andy and Laurel posessed tranistional levels of understanding the NOS while Carla was uninformed about the NOS. All three understood the tentative NOS and felt it was important to teach about this aspect of the NOS. They also felt it was important to teach about the structure of scientific knowledge as it relates to the
relationships between hypotheses, theories, and laws. However, Andy was the only one of the three teachers who understood this realtionship correctly.
All three teachers also supported the uninformed position that TSM is an
important aspect of the NOS and believed that it should be taught to students. Andy was most influenced by TSM as evident by his “adding a day of models” to his discussion about TSM. His reflections during the summer institute he indicated that he wrestled with how to assimilate the modeling process with his views about TSM. Carla, while