Factors which influence Texas biology teachers' decisions to emphasize fundamental concepts of evolution

Despite the documented support from scientists and the science education community, many science teachers do not emphasize evolution in a manner commensurate with its status as a unifying and central theme in biology. Independent research projects in several states provided evidence to support this assertion as well as a 1989 survey of Texas biology teachers. An inherent weakness in the literature on the teaching of evolution is a lack of follow-up studies that chart changes in the emphasis on evolution in specific states, which would offer a more comprehensive profile of the teaching of evolution over a period of time. Further, the teaching of evolution has historically been surrounded by persistent and ongoing controversy. Teachers' decisions to emphasize (or to not emphasize) evolution are as likely to be shaped by this controversy as they are to be shaped by their knowledge of content. The purpose of this study was to explore and describe the emphasis on seven fundamental concepts of evolution in Texas biology classrooms with relationship to teachers' personal and contextual beliefs about teaching evolution.

Results were obtained from 175 Texas biology teachers, which represented a 30% return rate from a geographically proportional distribution of teachers from across the state. The results of this study indicated that Texas teachers did emphasize the concepts of diversity, natural selection, speciation, evidence for evolution, and descent with modification to a moderate to strong degree, or in one or more than one lesson throughout the course. Human evolution and pace and rate of evolution received little to some emphasis, or one lesson or fewer throughout the course. Given unlimited freedom to make decisions, the teachers would emphasize all seven of the concepts to a degree greater than the' emphasized in their classrooms. The beliefs that were related to teachers' decisions to emphasize evolution included beliefs about evolution and science, beliefs about student learning, support from the principal, and time. The beliefs that were related to teachers' chosen degree of emphasis on evolution given unlimited freedom included beliefs about evolution and science and beliefs about student learning.

A majority of the teachers agreed that evolution is a central and unifying concept in biology and that the concepts of evolution are supported by scientific evidence. However, a majority also agreed that evolution was a controversial topic for other people. Approximately half of the teachers did not know if the parents or the principal supported the teaching of evolution, but almost half of the teachers believed that their principal would ask them to de-emphasize evolution if the parents protested against it.

Overall, this study concluded that Texas biology teachers did not emphasize evolution as a central and unifying concept, but given the choice, they would emphasize evolution more. Teachers' perceptions of the controversial nature of evolution could, in part, be related to the discrepancy between the current and chosen emphasis that the concept receives in classrooms. Other factors that influenced teachers' decisions were beliefs about the role of evolution in science and beliefs about the capacity and interest of students to learn about evolution. To a lesser extent, beliefs about support from the principal and beliefs about time limitations also influenced teachers' decisions to emphasize evolution.