Engaging elementary students in evidence-based reasoning is an essential aspect of science and engineering education. Evidence-based reasoning involves students making claims (i.e., answers to questions, or solutions to problems), providing evidence to support those claims, and articulating their reasoning to connect the evidence to the claim. In this article, the authors describe the way in which video segments from affordable, pocket-size, handheld, digital video cameras can be used to support evidence-based reasoning as students design model rock-and-mortar walls. They believe that with appropriate instructional technology, teachers can determine where in the curriculum cameras can help students acquire evidence in meaningful and authentic ways--finding good reasons in science and engineering instruction for students to be caught on video! (Contains 4 figures.)