In today's digital world the Internet is becoming an increasingly predominant resource for science information, rapidly eclipsing the traditional science textbook in content area classrooms (Lawless & Schrader, 2008). The shift challenges researchers, educators, administrators, and policy makers to reconsider what it means to read and comprehend online science information. The research on digital literacy is still in its infancy and little is known about the strategies and processes students use when reading science content on the Internet. Even less is known about how at-risk readers comprehend digital science content. Therefore, this study addresses three research questions: (1) What strategies and processes do at-risk and average-achieving readers use as they locate information and generate meaning from science websites? (2) What navigational profiles emerge as at-risk and average-achieving readers construct traversals (unique online paths of information) they locate information and generate meaning from science websites? (3) What individual characteristics influenced students' strategies as they locate information and generate meaning from science websites? Participants were six ninth-grade students in general education biology classrooms. Three were average-achieving readers and three were at-risk readers based on assessments of reading comprehension in traditional print-based texts. The students engaged in a three-day research project about the rainforest biome, locating information online, taking notes, and constructing an information brochure about the rainforest for peers. Data measures prior to and during the research included an Internet use survey, verbal protocols, screen captures of online activity, oral reading fluency assessments, and prior knowledge and topic engagement surveys. Quantitative descriptive and univariate analyses as well as qualitative abductive coding were employed over multiple phases to analyze the data. First, the results suggest that students employed a variety of online reading comprehension strategies in complex and dynamic ways. Among the many strategies revealed, the group of self-regulatory strategies (planning, predicting, monitoring, and evaluating) played a significant role, influencing students' use of all other strategies for locating and generating meaning from science websites. Second, the results also suggested that patterns of strategy use could be examined as unique navigational profiles. Rather than remaining fixed, the navigational profiles of each student altered in response to tasks and research methods. Importantly, all at-risk readers revealed more effective navigational profiles on Day 3 when they were forced by design of the task to attend to project goals and employ more self-regulatory strategies. Third, the results revealed that traditional reading comprehension strategies and prior knowledge of the rainforest also influenced online reading comprehension. Specifically, the at-risk readers with the lowest reading comprehension, oral reading fluency, and prior knowledge scores were more likely than the average-achieving readers to encounter issues in online texts that resulted in constructing ineffective traversals, or online reading paths, and spending significant time investing in online reading that was irrelevant to the research project. Ultimately, this study advanced the understanding about online reading comprehension for average-achieving and at-risk readers in science classrooms, contributing to a gap in the research, suggesting implications for practice, and promoting future research questions. [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.]