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As the use of computers in education increases, adaptive learning platforms are becoming more common. However, these adaptive systems are typically designed to support acquisition of declarative knowledge and/or procedural fluency but rarely address conceptual learning. In this work, we developed the Crystallography Adaptive Learning Module (CALM) for materials science to provide students a tool for individualized conceptual learning. We used a randomized quasi‐experimental design comparing two instructional designs with different levels of computer‐provided direction and student agency. Undergraduate students were randomly assigned to one of two different instructional designs; one design had students complete an individualized, adaptive path using the CALM (N = 80), and the other gave students the freedom to explore CALM's learning resources but with limited guidance (N = 85). Within these two designs, we also investigated students among different cumulative grade point average (GPA) groups. While there was no statistically significant difference in the measure of conceptual understanding between instructional designs or among the groups with the same GPA, there is evidence to suggest the CALM improves conceptual understanding of students in the middle GPA group. Students using CALM also showed increased participation with the interactive learning videos compared to the other design. The number of videos watched in each instructional condition aligns with overall academic performance as the low GPA group received the most assigned supplements but watched the least videos by choice. This study provides insight for technology developers on how to develop educational adaptive technology systems that provide a proper level of student agency to promote conceptual understanding in challenging STEM topics.

The ion exchange and point defect models are two prominent models describing the role of anions, such as chlorides, in the degradation of passive oxide films. Here the thermodynamic feasibility of critical steps of Cl-induced degradation of a hydroxylated α-Cr₂O₃(0001) surface, as proposed by these two models, are studied. Both models begin with Cl substitution of surface OH and H₂O, which becomes less favorable with increasing Cl coverage. The initial stages of Cl-induced breakdown of the α-Cr₂O₃depend on Cl coverage and the presence of O vacancy near the surface as follows: (1) neither Cl insertion (supporting the ion exchange model) nor Cr vacancy formation (supporting the point defect model) is feasible at low Cl coverages except in the presence of O vacancies near the surface, where Cl insertion is thermodynamically feasible even at low coverages, (2) in the absence of O vacancies, Cr vacancy formation becomes feasible from 10/12 ML onwards whereas Cl insertion by exchange with subsurface OH only becomes feasible at full coverage. This implies that at higher coverages Cl-induced degradation first initiatesthrough a vacancy formation mechanism, but both insertion and vacancy formation would be feasible at full coverage.