Pre-service biology teachers' knowledge structures of photosynthesis
Abstract/Summary
In keeping with issues on knowledge acquisition, this study attempted to probe pre-service biology teachers conceptual understanding of photosynthesis. Primarily, this study focused on particular mental models that the pre-service teachers employ in acquiring knowledge. Central to this was the previous knowledge of the learners on photosynthesis. To this end, it was deemed essential to recognize the learners alternative conceptions using Treagusts Two-tier Diagnostic Instrument on Photosynthesis and Respiration. Pre-service biology teachers conceptions of photosynthesis revealed their knowledge structures with respect to the way they organized ideas related to the concept. As the students knowledge structures could also be evident in the mental models being used, an interview protocol consisting of five situational problems dealing with the concept of photosynthesis was also employed on the subjects of the study. The problems and the corresponding probing questions helped generate data on pre-service teachers understanding of the concept. Interviews were also conducted and concept maps were generated based on the interview transcripts to further clarify the teachers knowledge structures. Results showed that the prevalence of alternative conceptions held by the students was a result of a knowledge-based understanding of photosynthesis: the subjects knew the details from memory but the relationships between and among the concepts seemed inaccurate. The students mental models as evidenced in the concept maps contained faulty ideas that verified those identified from the two-tier diagnostic instrument. Such faulty ideas were predominant across all year levels of Education majoring in Biology. Essentially, the respondents v conceptions of photosynthesis lacked a chemical understanding of the nature of matter they were mostly uncertain as to what happens to carbon dioxide and water in chemical reactions involved in photosynthesis. Moreover, the respondents lack an understanding of a particular substances function inside a plant. Most students failed to demonstrate such understanding in their mental models. Primarily, learning photosynthesis necessitates developing appropriate functional explanations and definitions. Generally, incomplete and faulty mental models demonstrating the subjects knowledge structures were observed.
