This article examines how emergent bilingual students used gestures in science class, and the consequences of students' gestures when their language repertoire limited their possibilities to express themselves. The study derived from observations in two science classes in Sweden. In the first class, 3rd grade students (9-10 years old) were involved in a unit concerning electricity. The second class consisted of 7th-grade students (13-14 years old) working with acids and bases. Data were analyzed by using practical epistemological analysis (PEA). When students' language proficiency limited their possibility to express themselves, using gestures resulted in the continuation of the science activities. Furthermore, both peers and teachers drew on the used gestures to talk about the science content. In some situations, the meaning of the gestures needed to be negotiated. Regardless, the gestures were always related to language. Both students and teachers participated in this process, but the teachers directed the communication toward the goal of the lessons: learning how to talk science. The study contributes to the field by showing the importance of paying attention to and valuing bilingual students' use of gestures as a way to express scientific knowledge. In addition, it demonstrates how teachers might draw on students' gestures to teach science and discusses the importance of creating multimodal learning environments.