A cooperative-learning jigsaw-style activity was developed to create opportunities for introductory organic chemistry students to discuss and decipher 1 H NMR spectra. Students cooperatively interpreted spectra that contained both pure and mixed solvents, building consensus through explanation and argumentation on what each spectrum represented. Through participating in this cooperative learning activity, students refined their ability to analyze complex, crude spectra that typically contained contaminants. The activity was designed to engage students in decoding data that are more realistic and applicable to research laboratories, where spectra are oftentimes difficult to interpret due to impurities such as unevaporated solvents and byproducts along with their intended product. Student perceptions of the activity were captured from reflective discussion in class and an end of course survey. Most students reported a shift in thinking about how they approached analyzing NMR spectra and found the activity helpful in learning to interpret spectra of complex mixtures.