Students access the prelectures by using a web browser to view animated lecture slides. The navigation of the slides is controlled by an Adobe Flash program such that at a few points during the lecture, the student is presented with a (usually conceptual) multiple-choice question on the current material. If the student answers correctly, they are given an explanation of the answer and can proceed to the next slide. If the student answers incorrectly, they are given an explanation of why their choice is incorrect and, depending on the specific implementation, is either immediately given another try at the question or is presented with a different question that must be answered correctly before they get another try at the original question. In any case, once they answer the initial question correctly, they can proceed to the next slide.