Elementary teachers can integrate social studies into their curriculum through thematic or interdisciplinary units. This study explores fourth-grade students’ responses to a month-long, structured inquiry. For two weeks, fourth-graders engaged in multiple readings of five secondary and fourteen primary sources using closed- and open-ended analysis questions and extemporaneous, text-based writing. For another two weeks, the writing process guided students through concept mapping, skeleton outlining, peer- and teacher-review, and revision. Three researchers examined students’ writings for criticality, complexity, and clarity. Findings yielded positive, statistically significant correlations between secondary source usage and historical significance, secondary source usage and continuity-and-change, and primary source usage and contextualization. Positive, weak correlations appear between primary source usage and sourcing. No relationship appears between corroboration and other variables. Meaning is extrapolated for classroom practice and applied to seminal studies. Limitations include a small sample of largely homogeneous, inexperienced students.