Introduction
In simulation, students often observe their peers perform a task. It is still unclear how different types of instructional guidance can turn the observational phase into an active learning experience for novices. This mixed-method study aims to understand similarities and differences between use of collaboration scripts and checklists by observers in terms of cognitive load and perception of learning.

Methods
Second-year pharmacy students (N = 162) were randomly assigned to 1 of 4 conditions when observing a simulation: collaboration scripts (heuristic to analyze in dyads while observing), checklists, both, or no guidance. We measured observers' intrinsic and extraneous cognitive load and self-perceived learning and conducted focus group interviews.

Results
Intrinsic cognitive load was significantly lower for checklists (M = 3.6/10) than for scripts (M = 4.7/10) or scripts and checklists combined (M = 4.7/10). Extraneous cognitive load was significantly lower for checklists (M = 1.5/10) than for scripts combined with checklists (M = 2.6/10) or no guidance (M = 1.8/10). There was no statistical difference between conditions for self-perceived learning. Coding of focus group interviews revealed 6 themes on observers' perception of learning under different conditions of instructional guidance. Students explained that collaboration scripts felt more complex, whereas checklists were perceived as a simple fact-checking exercise. Observing the simulation, regardless of guidance, was a meaningful learning experience.

Conclusions
With or without guidance, observers are actively engaged with the simulation, but their effort differed depending on instructions. When choosing between checklists or collaboration scripts, educators should be guided by the type of simulation task.