摘要：Background: Graduate teaching assistants (GTAs) often lead laboratory and tutorial sections in science, technology, engineering, and mathematics (STEM), especially at large, research-intensive universities. GTAs’ performance as instructors can impact student learning experience as well as learning outcomes. In this study, we observed 11 chemistry GTAs and 11 physics GTAs in a research-intensive institution in the southeastern USA. We observed the GTAs over two consecutive semesters in one academic year, resulting in a total of 58 chemistry lab observations and 72 physics combined tutorial and lab observations. We used a classroom observation protocol adapted from the Laboratory Observation Protocol for Undergraduate STEM (LOPUS) to document both GTA and student behaviors. We applied cluster analysis separately to the chemistry lab observations and to the physics combined tutorial and lab observations. The goals of this study are to classify and characterize GTAs’ instructional styles in reformed introductory laboratories and tutorials, to explore the relationship between GTA instructional style and student behavior, and to explore the relationship between GTA instructional style and the nature of laboratory activity. Results: We identified three instructional styles among chemistry GTAs and three different instructional styles among physics GTAs. The characteristics of GTA instructional styles we identified in our samples are different from those previously identified in a study of a traditional general chemistry laboratory. In contrast to the findings in the same prior study, we found a relationship between GTAs’ instructional styles and student behaviors: when GTAs use more interactive instructional styles, students appear to be more engaged. In addition, our results suggest that the nature of laboratory activities may influence GTAs’ use of instructional styles and student behaviors. Furthermore, we found that new GTAs appear to behave more interactively than experienced GTAs. Conclusion: GTAs use a variety of instructional styles when teaching in the reformed laboratories and tutorials. Also, compared to traditional laboratory and tutorial sections, reformed sections appear to allow for more interaction between the nature of lab activities, GTA instructional styles, and student behaviors. This implies that high-quality teaching in reformed laboratories and tutorials may improve student learning experiences substantially, which could then lead to increased learning outcomes. Therefore, effective GTA professional development is particularly critical in reformed instructional environments.
关键词：Graduate teaching assistants;Reformed laboratories and tutorials;Science laboratory and tutorial instruction;Professional development;Undergraduates;
