Technology and a variety of resources play an important role in students' educational lives. Vygotsky's (1987) theory of tool mediation suggests that cultural tools, such as computer software influence individuals' thinking and action. However, it is not completely understood how technology and other resources influence student action. Middle school students are a particularly an understudied population. This qualitative study examined how material and psychological tools, including the presentational software tools "PowerPoint" and "Prezi" mediate middle school students' actions when conducting research for two Earth Science research projects. Six eighth-grade students recorded computer screencasts and dialogue while conducting their research. I collected data from transcripts of computer screencasts, student interviews, and artifacts. Prior to coding, I established four major themes with 20 sub-categories. The four themes were content knowledge, previous tool use, resource use, and tool use. I segmented and coded the transcripts to reflect which different tools mediated student action. An analysis of the data revealed that library resources and the special features of "PowerPoint" and "Prezi" programs did not influence actions. Instead, I discovered that the assignment requirements and research topic content were the primary mediators of actions and behavior. However, despite the overall influence of the assignment requirements and topic content, each student employed different tools to complete each assignment. The results suggest that a variety of resources should be available to meet the individualistic tool use of students. The results also suggest that educators design less structured assignments that promote and encourage student centered learning and tool use. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]