Activities using volunteered geographic information (VGI), geospatial data generated by nonprofessionals, provide an instructional approach that allows participants to work with big data--large, complex data sets--in a noncompetitive, cooperative environment. Research suggests that humanitarian mapping activities offer an effective means of teaching data literacy. What factors motivate student participation in VGI activities, and how can librarians leverage an understanding of these motivations to offer attractive data literacy services? This project seeks an answer by measuring student motivation across three mapping events. The results show that participants are driven by both intrinsic and extrinsic factors.