Fostering scientific reasoning competencies: investigating impacts of cross- and within-content area experimentation using the competency triad

Educational standards and science education research suggest that experiments can be used to foster scientific reasoning competencies. So far, little is known about whether to sequence experiments from one or multiple content areas for this purpose. Therefore, we compared two sequences in an experimental study to investigate the influence of content areas of experiments on competencies' development: Based on the same underlying structure, the first, homogeneous sequence includes four kinetics experiments. The second, heterogeneous sequence involves experiments from kinetics, thermodynamics, and redox chemistry. A total of 97 students participating in undergraduate chemistry lab courses were randomly assigned to one of the sequences. The changes in competencies within the sequences were compared based on the 'competency triad' differentiating between underlying knowledge (dispositions), the use of this knowledge (processes), and the quality of the resulting investigations (products). The results show that both sequences are comparably suitable to foster scientific reasoning competencies. However, in the post-experiments, we found a tendency of increased inadequate or irrelevant content-related reasoning by bringing in and conflating concepts from previous experiments such as activation energy or the chemical equilibrium (in particular Le Chatelier's principle). We discuss these findings concerning the consequences of sequencing experiments for fostering scientific reasoning.