In recent years, the practice of using a second/foreign language to teach non-language content subjects (e.g. science) has become increasingly popular, especially in English-as-foreign-language (EFL) contexts. Such a practice can be categorised as 'Content and Language Integrated Learning' (CLIL). However, EFL learners may encounter difficulties in accessing content knowledge through English, especially with regard to the subject-specific academic literacy. Hence, content subject teachers may need to provide more scaffolding to help EFL learners in CLIL bridge the gap between everyday language and academic literacy. A genre-based approach, which emphasises contextualised language learning and use, serves as a useful framework to integrate content and language teaching in CLIL. This chapter shares an example of how university language specialists collaborated with science teachers in one secondary school in Hong Kong, where CLIL is practised. Drawing insights from the genre-based approach, the university-school collaborative team designed and tried out a set of materials to help grade 8 students write a piece of sequential explanation text. Lesson observations revealed how teachers integrated language scaffolding into their science lessons, and students' sample work and teachers' reflection showed that the materials were useful for helping the students develop science literacy. These findings yield significant implications for literacy development in science education and language across the curriculum in CLIL.