One approach to training is using scaffolding to assist the novice trainee in performing tasks while they develop fundamental skills. This paper describes the implementation and testing of visual scaffolding to support training of attentional management skills. The training tool was developed specifically for sensor operators of unmanned aerial systems (UAS) to learn attentional skills associated with managing the competing demands of UAS operational tasks. A key part of the training included attentional scaffolding—visual highlighting that was used to guide the trainee’s attention. Three different evaluations were conducted to assess performance while leveraging scaffolding: Two were performed with U.S. Navy and U.S. Coast Guard (USCG) sensor operators, and one was performed in a human-in-the-loop (HITL) study. In this paper, we detail the Navy and USCG studies, summarize the HITL study, and synthesize findings across the evaluations.