The purpose of this interpretive case study is to explore--through a close analysis of one fifth-grade class project--teacher's scaffolding and students' use of visual and linguistic modes when composing multimodally. Using Kress and van Leeuwen's multimodal theory of communication as a framework, this case study examines why teachers, whose social and cultural lives have been surrounded by a print-based perspective, need to develop depth of content knowledge when teaching students about multimodal representation. Two research questions guided this study: (a) in what ways did one teacher's discourse and pedagogical practices mediate students' communication with visual and linguistic modes within a fifth-grade classroom? and (b) using visual and linguistic modes of communication, in what ways did the students design and produce multimodal texts? Findings revealed the importance of teachers developing content knowledge of the affordances and limitations of different modes of communication, as well as understanding the metafunctions of these various modes.