Activities involving the two cited visualizations were part of our lab-centric data structures and programming methodology course, http://spring08.ucwise.org/about/guestAccess.php. (There were others as well, but the links are now broken.) The lab-centric course swapped lecture and discussion time for hands-on supervised lab time; students attended 1 hour of lecture and 6 hours of closed lab each week. The standard pattern of instruction was to motivate and introduce the details of the relevant algorithm, to note particularly complex algorithm features, then to direct students to the visualization web site. Suggestions for experimentation were provided, with instructions to keep track of interesting algorithm behavior. Students were encouraged to work in partnership. Some follow-up questions focused on differences between the version of the algorithm explained to students and the version implemented in the visualization; others asked how, if at all, the animations clarifed the complex aspects of the algorithm described early. (We have not yet analyzed student responses to these questions.)