Summary: Learning to compute integrals via the various techniques of integration (e.g., integration by parts, partial fractions, etc.) is difficult for many students. Here, we look at how students in a college level Calculus II course develop the ability to categorize integrals and the difficulties they encounter using a card sort-resort activity. Analysis of the data required the use of several non-standard techniques which provided interesting insights into the ways students develop categories in mathematics. One finding of note is that students may need a significant amount of time “off topic” to allow sufficient time to fully organize their schema for integration.