This laboratory was developed by undergraduate students in collaboration with the course instructor as part of a peer-developed and peer-led lab curriculum in a general chemistry course. The goal was to explore the hypothesis that crystal violet lactone was responsible for the thermochromic properties of a sipping straw using a FT-IR for experimental determinations of vibrational frequencies, UV-vis to quantify the color change, and the software packages Spartan and Gaussian 09 for theoretical calculations.