Language Across Curriculum (LAC) in the narrow sense focuses on the role of language in subject specific learning and teaching. In addition to the many basic goals of Language-1, it leads to other forums of functional language use, to mastering new domains and discourse types and moving towards a more explicit or pre-scientific mode of thinking and communicating. In subject specific context language is used as a tool for cognitively demanding task and purposes. This can be seen as an application of the existing language profciency in new contexts and as an extension and transformation of this proficiency on to a higher or deeper level of cognitive-academic use.
New forms of language use are not only happening in one non-linguistic subject, but in all of them. Thus we are talking about a central educational experience which is substantial for the learner and which will have a marked effect on his or her self perception and learning biography. Although each non-linguistic subject requires slightly different competences which have to do with their specific ways of proceeding in gaining new insights and integrating them into the existing knowledge structures, there is also a large area of overlap in competence requirements between subjects.
Academic language skills and competences do not develop all by themselves, simply through their use in subject-specific contexts alone. Rather, they have to do sufficiently stimulated and trained through systematic development and language awareness raising measures. Only then can we hope for all of our students to arrive at a level of academic language use and dixcourse competence which will allow them to participate successfully in subject specific learning experiences, in discussions and developments of the respective disciplines. By extending the knowledge and skills already acquired through language-1 into subject specific language varieties and discourse competences a learner develop a basic form of plurilingualism.
In contrast, foreign language education aims at the acquisition of another (mostly second or third) language system or language repartoire in addition to that of Language-1, but it does so by focussing on the development of the respective language itself as a code or a system of rules. Consequently, foreign language education is more concerned with the development of Basic Interpersonal Communication Skills (BICS) than of Cognitive Academic Language Proficiency (CALP). In doing so it adds to the development of plurilingualism in its external or explicit form.