Writing across the curriculum (WAC) is a movement within contemporary composition studies that concerns itself with writing in classes beyond composition, literature, and other English courses. According to a comprehensive survey performed in 2006–2007, approximately half of American institutes of higher learning have something that can be identified as a WAC program. In 2010, Thaiss and Porter defined WAC as "a program or initiative used to 'assist teachers across disciplines in using student writing as an instructional tool in their teaching'". WAC, then, is a programmatic effort to introduce multiple instructional uses of writing beyond assessment. WAC has also been part of the student-centered pedagogies movement (student-centered learning) seeking to replace teaching via one-way transmission of knowledge from teacher to student with more interactive strategies that enable students to interact with and participate in creating knowledge in the classroom. This page principally concerns itself with WAC in American colleges and universities. WAC has also been important in Britain, but primarily at the K–12 level.