makes in his or her instruction.

Brown and Borko (1992) concluded that teaching mathematics from a conceptual perspective is very unlikely to occur unless a teacher has deep conceptual understanding of the mathematics subject matter at hand. Later, Manouchehri (1997) stated flatly that the research literature supports the notion that “in the absence of conceptual understanding of content, effective teaching is highly improbable.”

Few parallel studies exist for science education. Carlsen (1988) found that teachers with deeper conceptual understanding of science allowed their students to engage in discourse more often than teachers with weaker conceptual backgrounds. Carlsen also noted that teachers with greater understanding of content asked students a greater number of high-level questions, whereas teachers who did not know the material tended to dominate the classroom discussion.

Hashweh (1987) studied the effects of teachers’ knowledge of subject matter in biology and physics on teachers’ abilities to teach these subjects. He found that teachers with higher levels of content knowledge integrated pieces of that knowledge more often into their teaching. These teachers also recognized higher order principles in the discipline, and their instructional strategies reflected this depth of knowledge. Within their specialty, teachers with greater content knowledge wrote examination questions that focused less on recall and more on students being able to apply and transfer information. However, when they were teaching outside of their specialty, these teachers followed textbook chapters more closely and were less likely to recognize or address student misconceptions. Hashweh concluded that knowledge of subject matter contributed greatly to these teachers’ ability to translate a written curriculum into an active curriculum in biology and physics.

As was noted earlier in this report, some policymakers and teacher educators believe that prospective teachers should emphasize their preparation in subject matter at the expense of preparation in education. Do teachers who were majors in science or mathematics understand the subjects they teach better than teachers who were education majors? Ball and Wilson (1990) conducted a study at Michigan State University that examined this question with prospective elementary teachers before and after they had completed their teacher preparation programs. They looked at two groups, one composed of prospective teachers who had been prepared in a traditional preparation program, and the other composed of prospective teachers who had been prepared in an alternative program.