By definition, human-centered design relies on interaction with users. While interacting with users within industry can be challenging, fostering these interactions in a classroom setting can be even more difficult. This qualitative study explores the use of crowd-based design activities as a way to support student-user interactions online. We motivate these online methods through a survey of 27 design instructors, who identified common challenges of conducting student-user interactions in physical settings, including coordination constraints and geographical barriers to meeting in person. We then describe our research through design approach to create and test 10 activities in a classroom setting, including using Twitter for needfinding and using Reddit to brainstorm ideas with experts. Finally, we present an emergent framework outlining the design space for crowd-based design activities where students learn to use input from online crowds to inform their design work. We discuss plans to refine and expand the current set of activities for open access to instructors.