Often teachers ask their English language learners to confine themselves to using English as they explore ideas, frequently because the teacher does not know the child's first language. This case study tells the story of Jean-Charles who uses both his first language, Haitian-Creole, and English, to make clear to himself and to others, differences in the meaning and use of the terms grow and develop during a study of insect metamorphosis. It illustrates the connection between the conceptual and the linguistic, and how a child's first and second languages can function together as powerful resources for making meaning in science.