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In this eye-tracking experiment, we compared instructional videos with static signals, dynamic signals and no signaling in a within-subject design. We tracked eye movements from 28 undergraduate chemistry students while they were watching instructional videos about reaction mechanisms in the different signaling conditions. Further, we assessed students' cognitive load, as well as retention performance. We employed a Latin square design to control for sequencing and content effects of the instructional videos. Our data showed that dynamic signals helped students to better focus their attention to the relevant features of the representations virtually across the entire time of the video presentation. Furthermore, dynamic signals increased retention performance while they decreased extraneous cognitive load. Overall, our findings show the crucial role of pairing the signaling principle with the temporal contiguity principle in instructional videos to help students navigate through complex symbolic representations and improve their learning success.

Research in Organic Chemistry education has revealed students’ challenges in mechanistic reasoning. When solving mechanistic tasks, students tend to focus on explicit surface features, apply fragmented conceptual knowledge, rely on rote-memorization and, hence, often struggle to build well-grounded causal explanations. When taking a resource perspective as a lens, students’ difficulties may arise from either an unproductive or a missing activation of cognitive resources. Instructors’ explanations and their guidance in teaching situations could serve as a lynchpin to activate these resources. Compared to students’ challenges in building mechanistic explanations in Organic Chemistry, little is known about instructors’ explanations when solving mechanistic tasks and how they shape their targeted explanations for students in terms of the construction and embedding of cause–effect rationales. This qualitative study aims to contribute to the growing research on mechanistic reasoning by exploring instructors’ explanatory approaches. Therefore, we made use of the framing construct, intended to trigger certain frames with explicit instruction. Ten Organic Chemistry instructors (university professors and lecturers) were asked to solve case comparison tasks while being prompted in two scenarios: an expert frame and a teaching frame. Our analysis shows that there is a shift from instructors’ mechanistic explanations in the expert frame towards more elaborated explanations in the teaching frame. In the teaching frame, contrary to what might be expected, complete cause–effect relationships were not always established and instructors differed in how they shaped their explanations. Additional explanatory elements were identified in both frames and their shift in use is discussed. Comparing approaches between frames sheds light on how instructors communicate mechanistic explanations and allows us to derive implications for teaching Organic Chemistry.

Students are known to have various difficulties in dealing with organic reaction mechanisms. A systematic classification of these difficulties appears necessary to design appropriate support. This paper presents insights into whether and how Bloom's revised taxonomy can be used to classify student difficulties in dealing with organic reaction mechanisms. We conducted an interview study with 12 undergraduate chemistry students using problem-solving tasks on nucleophilic substitution and elimination reactions to provide examples to test the classification. In our attempt at systemization, student difficulties are perceived as unachieved learning objectives. The classification reveals that student difficulties pertain to different cognitive process and knowledge dimensions. Specific major difficulties occurred within each cell of Bloom's revised taxonomy and for individual students. Our analysis suggests that general support for dealing with reaction mechanisms might be less beneficial for some students and that more adapted support is needed. Our approach of using Bloom's revised taxonomy to classify student difficulties might also benefit other domains to better understand student difficulties and evaluate appropriate support.

Supporting students in building well-grounded explanations plays a crucial role in scientific practice. Research in organic chemistry education on students’ mechanistic explanations, however, has revealed various challenges. When solving mechanistic tasks, students experience difficulties when (I) deriving implicit properties from structural formulas, (II) inferring the influence of these properties on the reaction process, (III) comparing and weighing multiple variables, (IV) using structural properties to make a claim, and (V) linking a structural consideration to energetic considerations. Reasoning steps, namely, (I) and (II), can be considered essential for mechanistic explanations, whereas the other steps depend on the task format. One way of supporting learners in these reasoning steps is to provide an instructional explanation that in a guided manner models these steps in tutorial videos. In this study, the design of tutorial videos on substitution reactions, which addresses known students’ challenges, is reported. The tutorial videos were put to test in a qualitative pre/post-interview study with students of an undergraduate organic chemistry course (N = 12). While tutorial videos are widely used, little is known about the impact of explicitly designed instructional explanations in videos on students’ ability to build mechanistic explanations. Hence, the findings of this study aim to contribute to the growing area of mechanistic reasoning by analyzing how students alter their mechanistic explanations after watching explicitly designed tutorial videos. Differentiated content analysis reveals that students adapt different aspects outlined in the tutorial videos. Overall, students infer more structural properties and use these to make a claim after watching the videos. However, linking this claim to the energetics of a reaction seems to remain challenging. Recommendations for the use in teaching as well as further development possibilities of the videos are presented.

Reaction mechanisms commonly used in organic chemistry are a great challenge for students in terms of understanding the representation and inferring the appropriate chemical concepts. In order to s...

In den letzten Jahren sind in vielen Ländern Kompetenzmodelle entwickelt worden, welche als Referenzsysteme für die Festlegung und Überprüfung von Bildungsstandards dienen. In vielen Fällen bleibt es jedoch eine offene Frage, wie spezifische Kompetenzen valide und reliabel erfasst werden können. So existieren beispielsweise keine spezifischen Tests oder theoretischen Modelle, welche die Kompetenz im zentralen naturwissenschaftlichen Kompetenzbereich - Ordnen, Strukturieren, Modellieren (in der Folge nur noch kurz: OSM) - des Schweizerischen Kompetenzmodells für die Naturwissenschaften zuverlässig erheben oder beschreiben können. Als Beitrag zur Klärung entwickeln wir hier basierend auf theoretischen Überlegungen ein Modell hierarchischer Komplexität für den Kompetenzbereich OSM (MHC-OSM) im Inhaltsbereich Chemie. Das Modell umfasst fünf Kompetenzstufen, deren theoretische Fundierung im Detail beschrieben wird. Eine erste Einordnung des Modells durch einen Vergleich mit der aktuellen Version des Lehrplans 21 sowie mit den seit 2011 festgeschriebenen Grundkompetenzen für die Naturwissenschaften beziehungsweise der Bildungsstandards für den mittleren Schulabschluss in Deutschland zeigt eine gute Passung. Zum Schluss wird aufgezeigt, wie das Modell empirisch validiert werden könnte.