Teaching assistants' topic-specific pedagogical content knowledge in 1H NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy is an essential analytical tool in chemistry, and the technique is routinely included as a topic across the undergraduate chemistry curriculum. As a result of NMR's importance, classroom instruction of this topic has received considerable attention in chemistry education research. However, little is known about instructors' knowledge for teaching this topic. In order to better understand this knowledge, we investigated topic-specific pedagogical content knowledge in 1 H NMR spectroscopy among 20 chemistry teaching assistants at a large Midwestern university in the United States. A questionnaire was developed to provide an inferential measure of content knowledge and topic-specific pedagogical content knowledge in 1 H NMR spectroscopy for participants with a range of teaching experience. Data from the questionnaire were analyzed qualitatively and quantized using a rubric. The quantitative data were transformed using the Rasch model and statistically analyzed. Results from these analyses indicate that pedagogical content knowledge increased with teaching experience in 1 H NMR spectroscopy, suggesting that knowledge for teaching this topic is developed through practice. Additionally, the development of pedagogical content knowledge was found to depend upon content knowledge required for specific NMR sub-topics and problems. This finding suggests that the ultimate "grain-size," or domain-specificity, of pedagogical content knowledge may extend to the problem level. Results from this study have implications for how instructors may cultivate knowledge for teaching NMR spectroscopy, as well as for how pedagogical content knowledge may be more effectively incorporated into instructor training programs.