This study aims at examining how physics content is elaborated and negotiated in a classroom, where several students are second language learners. More precisely, the study aims at examining how the students are supported in developing subject specific knowledge (in this case the model of sound) and ways of describing and explaining the content in accordance with the discourse of science. Data consist of video and audio recordings, digital photographs and collected texts from four physics classrooms (students aged 14–15 years). Theoretically, the study takes its stance in social semiotics (cf. Halliday 1978; Selander & Kress 2010), where form and content are closely linked. The multimodal interaction between the teacher and students and between students, along with texts used and produced in the classroom were analyzed through systemic-functional linguistics (SFL) in order to identify signs of learning (Selander & Kress 2010). In parallel with the analyses of students' development of subject-specific descriptions and explanations, choices of resources that seem to enable or hinder such a development were also identified. The results show that the teacher and the students were engaged in activities that increased students’ opportunities to understand and express aspects of sound and the sound model a more subject-specific way. However, some observations indicate classroom practices that might constitute a hindrance for learning the content. The study has implications for ways of promoting second language learners’ learning in science and the importance of both using meaning-making resources in conscious ways and to discuss how these resources can be used in relation to content.