Courseware to teach about the interdisciplinary nature of the Earth system was constructed based on the concept of intersecting spheres, as illustrated by Venn diagrams. This inquiry-driven courseware, which was called the Zen of Venn©, was applied in an undergraduate capstone course at The Ohio State University over two years. Results from these applications reveal that individuals integrate between 2 and 3 topics at a time, which appears to be related to the fact that the complexity of integration increases geometrically relative to the number of intersecting spheres. An area for future research would be to test whether integrating 3 plus or minus 1 topics is a generalized cognitive limitation like memorizing “7 plus or minus 2 random items.” These data and observations imply that interdisciplinary courses or textbooks with many distinct topics are geared more toward memorizing than synthesizing. Consequently, to facilitate individualized discovery of knowledge (which is gained by establishing relationships between things that are known and unknown), interdisciplinary teaching materials should be designed in a manner that stimulates open-ended inquiry and integration with embedded sets of 4 or less topics.