In this article, the authors introduce a series of interconnected, inquiry-based activities from a fifth grade social studies curriculum, "My Place in Time and Space," which was developed in part through a Library of Congress Teaching with Primary Sources (TPS) Regional Grant Program--Eastern Region. These activities are designed to build students' disciplinary literacy skills through working with primary sources. Each inquiry asks students to take on the role of junior detective and to work with an explicit source analysis strategy to investigate themes of discrimination and equality in 20th century U.S. history. The three historical topics included in this article are child labor during the first quarter of the 20th century, the imprisonment of Japanese Americans during World War II, and the arrest of Rosa Parks, which sparked the Montgomery Bus Boycott of 1955-56. The individual inquiries support key dimensions within the Inquiry Arc of the College, Career, and Citizenship (C3) Framework for Social Studies State Standards. The article contains lesson summaries and primary sources for The Mystery of the Dirty Kids and The Mystery of the Evacuation Sale.