Video-based simulations: a valuable resource for chemistry teaching and educational research

The interface of a typical educational digital video is often limited to the play-pause and timeline console. In contrast, computer based simulators allow dynamic visualizing of hundreds of experimental outcomes. However, producing a digital video is increasingly simpler, cheaper and faster than making its simulator counterpart. Here we report a simple, yet effective, approach to make and use videos with simulation capabilities for both teaching and educational research purposes: on-screen data reading from a digital video, made by combining synchronous footage of the same experiment, taken with two cameras at different angles. Following this strategy, digital videos of acid-base titrations were recorded in an ordinary lab setup. These videos were embedded in three types of activities, presented in the following order: A1 a tutorial; A2, a classic simulator (with a spreadsheet); and A3, a decision-making scenario. A1 and A3 were annotated with an interactive layer over the video. A1 and A3 displayed the same representational repertory integrated by the video time-line: the titration curve, a bar chart of the chemical composition and the video itself. Also, A1 and A3 actively, but not explicitly, involved the reversible reaction concept in the video-embedded interactions. Although similar to A1, A3 was significantly more complex: it entailed interpreting different representations in decision making scenarios: "what reactant must be added to go from the current position on the titration curve to this system composition (displayed as bar chart)? HCl or NaOH?". At the end of both activities, users are prompted to chose, among three chemical reaction hypothesis, the one that best explained the simulated phenomena: stoichiometric only, static equilibrium and dynamic equilibrium. These resources were tested in a remote 8 h (2x 4 h) case based learning (Sá et al. 2007) teaching module for 265 undergraduate students from geology (32) and pharmacy (72) courses. Although considered laborious (79 %) and conceptually difficult (78 %), the module was regarded as useful (69 %) by the students. They also evaluated it as innovative (93 %) and were willing to have more activities alike (85 %). The conceptual profile (Solsona et al. 2003, Gonzáles, 2017) for the chemical equilibrium concept was also investigated in connection to the representational competence (Chang 2018). The analysis of students' answers suggest a close connection between the mobilization of the conceptual profile and the complexity of the representational task requested. Interestingly, in some cases, even when the reversibility hypothesis was indicated, it was not the actual working concept employed in the decision making activities. References: Chang, Sci. Edu. 2018, 102, p. 1129; Solsona et al. Int. J. Sci. Edu. 2003, 25, p.3.; González, EDUCERE 2017, 68, p. 113; Sá et al. Quím. Nova, 2007,30(3) p. 731. Committee for Research with Humans register number: 3.357.893.