ABSTRACT Explaining scientific phenomena by unpacking their underlying mechanisms poses many challenges for high‐school students. One central challenge is synthesizing the different parts of a mechanism into a coherent whole and identifying what information is still missing, or whether further learning is required. This study investigates how high‐school students learn about mechanisms while constructing mechanistic explanations in biology. Using the lens of epistemic cognition, we examined how students navigate information about biological mechanisms during learning, shifting between parts of the mechanism they have already understood and those that remain as black boxes. Sixty‐five students from four biology classes (Grades 10 and 11) participated in a group‐based inquiry activity designed to uncover the biological mechanism underlying sun tanning. As students freely navigated available information, they made epistemic decisions about which black boxes to unpack and which to leave unexplored. The analysis focuses on students' learning trajectories and the epistemic knowledge that informed these decisions. Our findings identified three distinct learning trajectories, indicating that students may follow different paths when learning about mechanisms. Each trajectory was associated with a particular combination of epistemic knowledge. We propose that these trajectories emerge because students' epistemic knowledge directs their attention to specific black boxes within a mechanism. Consequently, students prioritize the unpacking of different black boxes and thus follow distinct sequences of learning. We discuss the educational significance of these findings and their implications for evaluating incompleteness and supporting the construction of mechanistic explanations.
Molad et al. (Thu,) studied this question.