The use of computers to deliver course-related materials is rapidly expanding in most universities. Yet the effects of computer vs. printed delivery modes on students' performance and motivation are not yet fully known. We compared the impacts of Web vs. paper to deliver practice quizzes that require information search in lecture notes. Hundred and twenty two undergraduate students used either a web site or printed documents to answer 18 mathematics questions during a tutored session. A revised Web site was designed based on ergonomic criteria, to test the hypothesis that improved usability would decrease time spent on the task, the number of pages consulted, and students' perceived cognitive load. The group working with printed documents had the highest performance. Furthermore, students perceived the paper materials as less effortful to read, and expressed preference for printing lecture notes and questions. However, students appreciated having a Web site available. No differences were found between the two sites. We conclude that Web delivery imposed higher perceived cognitive load due to the need to read lengthy documents. We suggest possible ways to improve Web-based practice materials, such as simultaneous display of questions and lecture notes. (Contains 3 tables and 2 figures.)