Online learning has become a prevalent method of instruction in higher education. There are many reasons for this change in pedagogy, including rapid developments in technology, as well as the logistic challenges of enrolling in college, such as commuting and coordinating work schedules. The quality of online instruction and its impact on teacher preparation, however, has yet to be fully investigated. The purpose of this study is to add to the existing literature regarding online learning and its use in teacher preparation. This study, more specifically, compared the effects of differentiated use of a specific online learning environment, the IRIS Center for Training Enhancements (http://iris.peabody.vanderbilt.edu/index.html), on knowledge of teacher candidates in two sections of a "Teaching Exceptional Learners" course for general education undergraduate and graduate teacher candidates. Pre-and post-instructional concept maps were used to measure growth in knowledge in this counterbalanced study. Results indicate both methods of instruction, in-class and at-home, with the IRIS modules are effective for increasing the knowledge base of general education teacher candidates. Analysis of the data showed no significant differences in learning between the two methods. While preference of methods differed, overall, participants felt the IRIS modules were beneficial and made an impact on their learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]