Just as elementary students enter the science classroom with prior knowledge and experiences, so do preservice elementary teachers who enter the science methods classroom. Elementary science methods instructors recognize the challenges associated with preparing teachers for the science classroom. Two of these challenges include overcoming limited science content understanding and a low science teaching efficacy. Based upon research in science misconceptions, conceptual change theory, formative assessment, and science teaching efficacy, this design experiment explored the use of formative assessment in an authentic learning environment to address some of these challenges. As a case study, the goal was to identify two specific topics in science which the preservice teachers did not understand and to model consistent use of formative assessment to guide instruction in those science topics for six weeks. The research questions for this study sought to explore the design of the class while also exploring students' understanding of the science content and their understanding of formative assessment. One specific question was whether the formative data could differentiate between deeply held student misconceptions in science and incomplete science understanding. In addition, data was collected to measure changes in science teaching efficacy as well as preservice teachers' desire to use formative assessment in their own future classrooms. Based upon student interviews and a final content quiz, the participants in this study did show improved science content understanding in the areas of plant food/energy and plate tectonics. The course design implemented a variety of formative assessment tools including formative assessment probes, student science notebooks, student concept maps, a non-graded quiz, and more. The STEBI-B survey identified improved science teaching efficacy among the participants. Student final essays indicated improved understanding of formative assessment and students also expressed a desire to incorporate formative assessment into their future teaching. Final reflections on this case study recognize the value of formative assessment as a means for improved communication between students and teachers about student understanding in an effort to provide and model more effective science instruction. [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.]