In 2 experiments, 241 undergraduates with low domain knowledge viewed a tutorial on how to use Packet Tracer (PT), a computer-networking training simulation developed by the Cisco Networking Academy. Participants were then tested on retention of tutorial content and transfer using PT. Tutorial modality (text, narration, or narration plus text) was varied betweens subjects in both experiments, and simulation interface restriction (restricted or unrestricted) was varied between subjects only in Experiment 1. When PT's interface was unrestricted, students who received the narration tutorial performed better on the transfer task compared with students who received the text tutorial (statistically significant in Experiment 1 but not in Experiment 2). These findings extend the cognitive theory of multimedia learning (Mayer, 2005) by testing modality effects in new contexts and further specifying conditions of its applicability. (Contains 4 figures and 2 tables.)