The three interview prompts discussed in the paper are in Box 1. The problems were presented from A to C. Resonance is the key resource required to answer each prompt. The structures are conjugated with nonequivalent resonance structures accounting for the 170 observed properties. The lone pairs on the nitrogen atoms in C were not provided to gauge whether students could recognize what they were missing. The interview prompts were developed based on textbook problems (Problem A) or exam questions administered by the PI.