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Equilibrium is a challenging concept for many, largely because developing a deep conceptual understanding of equilibrium requires someone to be able to connect the motions and interactions of particles that cannot be physically observed with macroscopic observations. Particle level chemistry animations and simulations can support student connections of particle motion with macroscopic observations, but for topics such as equilibrium additional visuals such as graphs are typically present which add additional complexity. Helping students make sense of such visuals requires careful scaffolding to draw their attention to important features and help them make connections between representations ( e.g. , particle motion and graphical representations). Further, as students enter our classrooms with varying levels of background understanding, they may require more or less time working with such simulations or animations to develop the desired level of conceptual understanding. This paper describes the development and testing of activities that use the PhET simulation “Reactions and Rates” to introduce the concept of equilibrium as a student preclass activity either in the form of directly using the simulation or guided by an instructor through a screencast. The pre-post analysis of the two most recent implementations of these activities indicates that students show improved understanding of the core ideas underlying equilibrium regardless of instructor, institution, or type of instructional environment (face to face or remote). We also observed that students were more readily able to provide particle level explanations of changes in equilibrium systems as they respond to stresses (such as changes to concentration and temperature) if they have had prior course instruction on collision theory. Lastly, we observed that student answers to explain how an equilibrium will respond to an applied stress more often focus on either initial responses or longer-term stability of concentrations, not on both key aspects. 

Abstract Background Engagement with particle-level simulations can help students visualize the motion and interactions of gas particles, thus helping them develop a more scientifically accurate mental model. Such engagement outside of class prior to formal instruction can help meet the needs of students from diverse backgrounds and provide instructors with a common experience upon which to build with further instruction. Yet, even with well-designed scaffolds, students may not attend to the most salient aspects of the simulation. In this case, a screencast where an instructor provides narrated use of the simulation and points students towards the important observations may provide additional benefits. This study, which is part of the larger ChemSims project, investigates the use of simulations and screencasts to support students’ developing understanding of gas properties by examining student learning gains. Results This study indicates that both students manipulating the simulation on their own and those observing a screencast exhibited significant learning gains from pre- to post-assessment. However, students who observed the screencast were more than twice as likely to transition from a macroscopic explanation to a particle-level explanation of gas behavior in answering matched pre- and post-test questions. Eye-tracking studies indicated very similar viewing and usage patterns for both groups of students overall, including when using the simulation to answer follow-up questions. Conclusion Significant learning gains by both groups across all learning objectives indicate that either scaffolded screencast or simulation assignments can be used to support student understanding of gas particle behavior and serve as a first experience upon which to build subsequent instruction. There is some indication that the initial use of the screencast may better help students build correct mental models of gas particle behavior. Further, for this simulation, watching the instructor manipulate the simulation in the screencast allowed students to subsequently use the simulation on their own at a level comparable to those students who had manipulated the simulation on their own throughout the assignment, suggesting that the screencast students were not disadvantaged by not initially manipulating the simulation on their own. 

Simulations have changed chemistry education by allowing students to visualize the motion and interaction of particles underlying important chemical processes. With kinetics, such visualizations can illustrate how particles interact to yield successful reactions and how changes in concentration and temperature impact the number and success of individual collisions. This study examined how a simulation exploring particle collisions, or screencast employing the same simulation, used as an out-of-class introduction helped develop students’ conceptual understanding of kinetics. Students either manipulated the simulation themselves using guided instructions or watched a screencast in which an expert used the same simulation to complete an assignment. An iterative design approach and analysis of pretest and follow up questions suggests that students in both groups at two different institutions were able to achieve a common base level of success. Instructors can then build upon this common experience when instructing students on collision theory and kinetics. Eye-tracking studies indicate that the simulation and screencast groups engage with the curricular materials in different ways, which combined with student self-report data suggests that the screencast and simulation provide different levels of cognitive demand. This increased time on task suggests that the screencast may hold student interest longer than the simulation alone.