Translanguaging in science includes the use of semiotic repertoires complete with non-linguistic modes of meaning (e.g. gesture, tactile) that until recently have gone unnoticed in research into content language integrated learning (CLIL). Currently, there are calls for classroom research in CLIL settings that examines the semiotic processes in the spontaneous translanguaging of emergent bilinguals. In response, this study aims to expand bilingualism research by investigating the ways in which fifth-grade emergent bilinguals' draw from their semiotic repertoires when translanguaging in content-based science lessons. Multimodal transcriptions made from video recordings of the lessons allow a cross-case analysis of the emergent bilinguals' shifts from oral to gestural or tactile modes during a biology and physics unit. Findings illustrate that emergent bilinguals use non-linguistic modes to aid their science discourse in four distinct ways: replacement, support, demonstration and imitation. For instance, gestural and tactile meanings replace unknown everyday words and science language during demonstrations. A fine-grained analysis of the semiotic units shows that tactile moves, gesticulations, pantomime and imitation each play a role in the semiotic processes involved when translanguaging in a content-based science class. They allow the expression of ideas, the mediation of language and the unaided flow of discourse.