Using web-based instruction to improve large undergraduate biology courses: An evaluation of a hybrid course format Samuel Riffell a, * , Duncan Sibley b a Department of Zoology, Michigan State University, East Lansing, MI 48824, USA b Center for Integrative Studies – General Science, Michigan State University, East Lansing, MI 48824, USA Accepted 16 January 2004 Abstract We developed a hybrid course format (part online, part face-to-face) to deliver a high-enrollment, in- troductory environmental biology course to resident (living on or near campus), non-science majors at a large, public university. The hybrid course was structured to include bi-weekly online assignments and weekly meetings in the lecture hall focused on active-learning exercises. To evaluate the effectiveness of the web-based component of the hybrid course, we taught the hybrid course simultaneously with a traditional course in which we used passive lectures to cover material in the online assignments. Both courses received the same active-learning activities in class. Students in the hybrid course reported that the quality of in- teraction with the instructor was high, that they read the text more often and studied in groups more frequently. Performance on a post-course assessment test indicated that the hybrid course format was better or equivalent to the traditional course. Specifically, online assignments were equivalent to or better than passive lectures, and that active-learning exercises were more effective when coupled with online activities. Performance gains were greater for upperclassmen than for freshmen, indicating that hybrid course formats might be a superior option for upperclassmen when satisfying general science requirements. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Evaluation of CAL systems; Improving classroom teaching; Interactive learning environments; Post- secondary education; Teaching/learning strategies * Corresponding author. E-mail address: sriffell@cfr.msstate.edu (S. Riffell). 0360-1315/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.compedu.2004.01.005 Computers & Education 44 (2005) 217–235 www.elsevier.com/locate/compedu