Over the last several years, iPads have become increasingly popular in the classroom. The number of available apps that could be used in the mathematics classroom are countless, but some make better mathematical learning tools than others. This research presents a set of sixteen criteria that can be used to evaluate the potential of an iPad app to be an effective mathematical learning tool. A review of the existing literature on digital learning objects and on iPads and tablet PCs in the classroom is conducted. The evaluation instrument is presented, along with a discussion of each of the sixteen criteria. The instrument is then applied to seven apps designed for learning algebraic concepts. From this sample of seven apps, common themes are examined. Implications for educators, designers, and for future research are discussed.