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ABSTRACTIdentifying instruments and surveys to address geoscience education research (GER) questions is among the high-ranked needs in a 2016 survey of the GER community (St. John et al., 2016). The purpose of this study was to develop and validate a student-centered assessment instrument to measure course experience in a general education integrated science course. A one-shot case study of pre-experimental design (Creswell, 2009, 2014) was used to understand student experiences in a large-enrollment course with digital content integration, including out-of-class video, online presentations, and warm-up questions, as well as in-class video paired with discussion and small group activities. In two sections taught by the same geoscientist, 209 students accessed course content in an online learning management system prior to classroom instruction. We adapted the 36-item Course Experience Questionnaire (CEQ; Wilson et al., 1997) to a Web-based survey. We conducted statistical analysis on the CEQ responses, including item factor analysis, examination of communalities and measures of association, confirmatory factor analysis, and reliability and stability testing through bootstrap resampling. The statistical analyses indicate that the results in this study are comparable to those from other cultural contexts and subject areas. Given the moderate fit of the model and reasonably stable results, we propose that the core indicators of the CEQ constructs, including Appropriate Workload, Clear Goals and Standards, Generic Skills, Good Teaching, and Emphasis on Independence are sufficient to assess students' course experiences in general education science settings. These results provided moderately to strongly valid information that can help instructors in designing their technology-integrated classes, although further study with a larger sample population would be beneficial. From this study we conclude that students' perceptions of their course experiences are closely related to their development of problem-solving and analytical skills, clear course expectations to direct their own study plans, their preference for a motivating instructor, the opportunity to have a variety of learning choices, and their workload. We propose the use of a 25-item version of the CEQ that is appropriate for formative assessment in discipline-specific STEM introductory classes, including geoscience classes.

An extensive analysis of multiple ScSreverberation data sets sampling regions of active or recent subduction reveals evidence of midmantle reflections apparently stemming from fragments of subducted slabs or from the interaction between subducted slabs and the surrounding mantle. Transition zone reflectors are detected beneath the southwest Pacific Ocean and Melanesia with mean depths of ∼850 and 1100 km in the majority of source–receiver corridors crossing the study area. The observations are most spatially coherent beneath the Coral and Tasman Seas. Coincident observations of the two reflectors along most seismic corridors suggests (but does not mandate) the existence of two distinct reflectors rather than bimodal depth distribution of a single reflector or distributed scatterers. Beneath North America, reflectors at depths of ∼1380 and 1530 km are seen in the midcontinent region; further east, the reflections are shallower, with depths near 940 and 1130 km. Unlike the southwest Pacific, the reflectors are not paired in any of the individual source–receiver corridors. This and the depth variability of the observations indicate that the reflector (or reflectors) in the Americas is (are) fragmented from west to east (transecting source–receiver corridors). The impedance contrasts of these features rival that of the 660‐km discontinuity, suggesting that individual fragments of the reflecting surfaces must be relatively continuous and flat from north to south (along individual corridors) to maintain a strong apparent impedance contrast. The reflections in both study areas are unlikely to be the result of slabs interacting with a chemical boundary layer or small‐scale scatterers within the midmantle. More likely these reflectors result from a pressure–temperature‐dependent phase transition within or around subducting slabs.