Advances in computing have awakened a century old teaching philosophy: learner-centered education. This philosophy is founded on the premise that people learn best when engrossed in the topic, participating in activities that motivate learning and help them to synthesize their own understanding. We consider how the object-oriented design (OOD) learning tools developed by Rosson and Carroll [5] facilitate active learning of this sort. We observed sixteen students as they worked through a set of user interaction scenarios about a blackjack game.