Medication safety is critical knowledge for licensure examination and practice, yet it remains a challenge for educators to develop effective activities for students to apply pharmacology concepts. Pharmacology is often taught through lecture and test format, but evidence shows students need opportunities for application to achieve deep learning and develop higher-order thinking skills. Cooperative learning strategies, which allow students to tackle work just beyond their individual abilities, are often used to foster higher-order thinking skills. Think-pair-share is a cooperative learning strategy in which students work together, usually during class, to share knowledge about a question or assignment. We used this approach to teach asthma medications, common medication errors, and drug-drug interactions to nurse practitioner students. Student pairs identified 10 errors in a patient's report of home asthma medication use from a clinic note. Pairs of students then formed "squares," compared responses, and discussed rationales. Correct responses were provided by faculty and discussed as a group at the end. Student feedback indicates the activity was a useful and engaging way to apply pharmacological content. Students valued the use of the "square" and reported that part of the approach was helpful in validating answers when initial pairs disagreed.