In this activity, learners are asked to complete sample diagnostic assessments that model how nongraded, preinstructional “tests” support learner-centered curriculum and instruction. These kinds of tests, the specific questions asked, and the misconceptions and conceptual holes that are elicited will likely be discrepant events for students and teachers alike. Although not conventional discrepant-event demonstrations by themselves, diagnostic assessments can be used in conjunction with inquiry-oriented demonstration-experiments and hands-on explorations.