Abstract: The online learning system provides customized answer explanations based upon a user's incorrect response to a multiple choice question. The explanations identify trick answers and how to avoid them, incorrect assumptions, and/or incorrect calculations that caused the student to reach the incorrect solution. The system also tracks the user's progress and provides customized feedback based on measurable aspects of the user's progress. Course material is provided by the system using a video game and/or social gaming type of user interface that fosters competition to motivate students and also uses incentives such as experience points, levels of mastery, and the ability to earn virtual goods or unlock challenges as the user progresses.