In a meta-analysis of 164 studies, Alfieri, Brooks, Aldrich, and Tenenbaum (2010) found that assisted discovery learning was more effective than explicit instruction or unassisted discovery learning and that explicit instruction resulted in more favorable outcomes than unassisted discovery learning. In other words, "unassisted discovery does not benefit learners, whereas feedback, worked examples, scaffolding, and elicited explanations do." The primary aim of the present research was to compare structured discovery, unstructured discovery (haphazard practice), and business-as-usual in fostering fluency with add-1 and doubles combinations. Interventions were conducted during the school day as pullout, 1-on-1, training sessions at five elementary schools in two school districts serving a medium-size Mid-western city. Participants in the unstructured add-1 training achieved comparable gains in fluency with n+1/1+n items as those in the structured add-1, and children in these groups achieved greater fluency with n+1/1+n items than did peers with active-control group (cf. Alfieri et al., 2011). In contrast, the structured doubles condition was more effective than the unstructured practice group in promoting transfer to unpracticed doubles. (Contains 4 figures and 5 tables.)