The world is fast becoming increasingly digital, networked, and mobile. The use of mobile devices is a growing educational trend and determines how knowledge is taught and used when teaching and learning. This article presents the results of a comparative analysis of web and mobile educational content, which focuses on instructional issues that affect learning in a mobile context--namely, length, density, complexity, purpose, and structure. It then demonstrates that mobile content is shorter, denser, and more complex than the content of other types of educational media, and it proposes a critical assessment of how such content should be designed.