Drawing from data generated during the 2016-2017 academic year, this study centred on U.S. children's design of two critical literacies compositions--a letter to Congress and a persuasive multimodal text. Situated within an integrated unit focused on (im)migrants, children asked legislators to act on the GOP Administration's proposed border wall and the #MuslimBan. Simultaneously, their teacher took steps to engage students in critical literacies conversations about access in/to the United States. Using a case study design, I investigated the following: "How might traditional perceptions of 'expert' shift as children engage in critical literacies using varied materials and technologies?" Specifically, I highlight how, by engaging an expansive skill set of communicative practices, children designed texts and enacted identities related to civic agency. Through multimodal composing, one nine-year-old white boy exemplified how children highlight knowledge beyond what is captured in a written text. His multimodal response illuminated his deep understanding of the obstacles faced by (im)migrants as they traverse boundaries. To alleviate such challenges, he "invented" both a transportable water filter cup and a fishing tool and engaged in critical making. When provided with opportunities to compose multimodally, the child--a white boy marked as "behind" in literacy--demonstrated rich content knowledge not readily visible in his written responses. His compositions disrupted understandings of expert with regard to elementary writing and critical literacies.