This project combines developmental and computational approaches to examine how humans develop conceptual understanding in informal science environments. The proposal advances a domain-general learning theory that explains how children form hypotheses when they encounter a new learning problem, how they seek out evidence to test those hypotheses, how they update their beliefs in response to new evidence, and how then develop new hypotheses, gather new information, and so on. This basic model is termed the "sensemaking loop" of cognitive understanding. To evaluate this model, this project will develop iPad-based experimental paradigms for testing each step of this learning process in children ages 5-10, which will be implemented in the Discovery Room at the American Museum of Natural History. This project will reveal the developmental and computational processes that underlie conceptual sensemaking and yield recommendations for improving education environments to maximize the development of understanding.