Teaching content through a foreign language presents students with the double challenge of having to understand new concepts and of doing so through a foreign language. To be successful in meeting this challenge teachers have to adapt their teaching style and the tasks they work on with their students. Often, however, they do not know how to do so, since, while research offers some guidelines for task design, this tends to be rather removed from the teachers' real-world need so as to be of little use to them, so that teachers feel they have to resort to students' L1 when working on difficult concepts. In this article I try to bring together the proposals made by researches in different areas that can contribute to helping teachers adapt the tasks they use in class, and thus make it possible for students to meet the double challenge of bilingual teaching with good possibilities of success. (Contains 1 footnote.)