An investigation into preservice teachers' information evaluation skills at a large university suggests that formative assessment can improve student achievement. Preservice teachers were asked to apply information evaluation skills in the areas of currency, relevancy, authority, accuracy, and purpose. The study used quantitative methods to assess preservice teachers' evaluation skills as demonstrated within the context of a final project, or summative assessment, in an elementary education course. The authors compared the preservice teachers' and researchers' evaluations to analyze final projects from two semesters. When asked to evaluate the sources cited in a final project for an education methods course, preservice teachers who received formative feedback from librarians improved in most information evaluation areas. Formative assessment is explored as a tool for improving information literacy instruction. (Contains 3 tables.)