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The use of the flipped classroom approach in higher education STEM courses has rapidly increased over the past decade, and it appears this type of learning environment will play an important role in improving student success and retention in undergraduate chemistry "gatekeeper" courses. Many adopters of the flipped classroom structure see the greatest benefit originating from the additional time this format provides for the implementation of student-centered learning activities during the classroom period. However, results from recent quasi-experiments suggest that improved course performance for students in flipped classroom environments has a significant contribution from the online preclass activities. In order to compare the impact of the preclass online learning environment to the in-class collaborative activities typically done in a flipped classroom, a randomized controlled trial (RCT) was conducted with student volunteers. A two-day organic chemistry stereochemistry unit was delivered to students who were randomly assigned to "flipped classroom" and "traditional lecture" treatment groups. Performance gains were measured after each phase of the instructional intervention for both treatment groups, and these gains were compared to students from a randomly assigned negative control group. A mixed-methods ANOVA indicates that under these experimental conditions the online learning component appears to account for most of the improvement in posttest scores observed in the flipped classroom treatment. These results suggest optimizing the design of the asynchronous online learning environment will positively impact student performance outcomes. Therefore, this component of the flipped classroom deserves more attention from instructional designers and classroom practitioners.

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Cognitive science has primarily studied the mental simulation of spatial transformations with tests that focus on rigid transformations (e.g., mental rotation). However, the events of our world are not limited to rigid body movements. Objects can undergo complex non-rigid discontinuous and continuous changes, such as bending and breaking. We developed a new task to assess mental visualization of non-rigid transformations. The Non-rigid Bending test required participants to visualize a continuous non-rigid transformation applied to an array of objects by asking simple spatial questions about the position of two forms on a bent transparent sheet of plastic. Participants were to judge the relative position of the forms when the sheet was unbent. To study the cognitive skills needed to visualize rigid and non-rigid events, we employed four tests of mental transformations--the Non-rigid Bending test (a test of continuous non-rigid mental transformation), the Paper Folding test and the Mental Brittle Transformation test (two tests of non-rigid mental transformation with local rigid transformations), and the Vandenberg and Kuse (Percept Motor Skills 47:599-604, 1978) Mental Rotation test (a test of rigid mental transformation). Performance on the Mental Brittle Transformation test and the Paper Folding test independently predicted performance on the Non-rigid Bending test and performance on the Mental Rotation test; however, mental rotation performance was not a unique predictor of mental bending performance. Results are consistent with separable skills for rigid and non-rigid mental simulation and illustrate the value of an ecological approach to the analysis of the structure of spatial thinking.

Science, technology, engineering, and mathematics (STEM) disciplines commonly illustrate 3D relationships in diagrams, yet these are often challenging for students. Failing to understand diagrams can hinder success in STEM because scientific practice requires understanding and creating diagrammatic representations. We explore a new approach to improving student understanding of diagrams that convey 3D relations that is based on students generating their own predictive diagrams. Participants' comprehension of 3D spatial diagrams was measured in a pre- and post-design where students selected the correct 2D slice through 3D geologic block diagrams. Generating sketches that predicated the internal structure of a model led to greater improvement in diagram understanding than visualizing the interior of the model without sketching, or sketching the model without attempting to predict unseen spatial relations. In addition, we found a positive correlation between sketched diagram accuracy and improvement on the diagram comprehension measure. Results suggest that generating a predictive diagram facilitates students' abilities to make inferences about spatial relationships in diagrams. Implications for use of sketching in supporting STEM learning are discussed.