No abstract

A critical aspect of teacher education is gaining pedagogical content knowledge of how to teach science for conceptual understanding. Given the time limitations of college methods courses, it is difficult to touch on more than a fraction of the science topics potentially taught across grades K-8, particularly in the context of relevant pedagogies. This research and development work centers on constructing a formative assessment resource to help expose pre-service teachers to a greater number of science topics within teaching episodes using various modes of instruction. To this end, 100 problem-based, science pedagogy assessment items were developed via expert group discussions and pilot testing. Each item contains a classroom vignette followed by response choices carefully crafted to include four basic pedagogies (didactic direct, active direct, guided inquiry, and open inquiry). The brief but numerous items allow a substantial increase in the number of science topics that pre-service students may consider. The intention is that students and teachers will be able to share and discuss particular responses to individual items, or else record their responses to collections of items and thereby create a snapshot profile of their teaching orientations. Subsets of items were piloted with students in pre-service science methods courses, and the quantitative results of student responses were spread sufficiently to suggest that the items can be effective for their intended purpose.

What follows is a practical guide for establishing the validity of a survey for research purposes. The motivation for providing this guide is our observation that researchers, not necessarily being survey researchers per se, but wanting to use a survey method, lack a concise resource on validity. There is far more to know about surveys and survey construction than what this guide provides; and this guide should only be used as a starting point. However, for the needs of many researchers, this guide provides sufficient, basic information on survey validity. The guide, furthermore, includes references to important handbooks for researchers needing further information.

Researchers need to know what is an appropriate sample size for interview work, but how does one decide upon an acceptable number of people to interview? This question is not relevant to case study work where one would typically interview every member of a case, or in situations where it is both desirable and feasible to interview all target population members. However, in much of qualitative and mixed-methods research and evaluation, the researcher can only reasonably interview a subset of the target population. How big or small should that subset be? This paper provides a brief explanation of why the concept of generalization is inappropriate with respect to the findings from qualitative interviewing, what wording to use in place of generalization, and how one should decide on sample size for interviews.

Science curricula and teaching methods vary greatly, depending in part on which facets of science are emphasized, e.g., core disciplinary ideas or science practices and process skills, and perspectives differ considerably on desirable pedagogies. Given the multi-faceted nature of science and the variety of teaching methods found in practice, it is no simple task to determine what teaching approaches might be most effective and for what purposes. Research into relative efficacy faces considerable challenges, with confounding factors, ambiguities, conflations, and lack of controls being threats to validity. We provide a conceptual framework characterizing the many teaching strategies found in practice as being variants of two fundamental contrasting epistemic modes, and we disentangle conflations of terms and confusions of constructs in both teaching practice and research. Instructional units for two science topics were developed in parallel in the alternative epistemic modes, differing in concept learning paths but otherwise equivalent. We conducted a randomized controlled study of the comparative efficacy of the two modes for learning core disciplinary ideas, using operationally defined active-direct and guided-inquiry teaching methods. Five middle school teachers taught each unit in both modes over 4 years of classroom trials in an 8-day summer program for eighth grade students. Student understanding of core ideas was assessed using pre-and post-tests, and learning gains were analyzed by mode, teacher, topic, and trial year. Although routes to concept understanding were very different in the two modes, eventual student learning gains were similar, within statistical variation. Efficacy variations between and within teachers were greater than between modes, indicating the importance of teacher effects on student achievement. Findings suggest that teachers need not be bound to one mode throughout and can flexibly decide on the pedagogical approach for each concept and situation, on several grounds other than efficacy of core content acquisition alone.