Since 2008, Sage has taught at the College of Teachers (now The Chartered College of Teaching) and was dean of academic affairs until 2014. She worked at Liverpool Hope University in 2007, where she taught communication in education, and at the University of Leicester, where she was a senior lecturer. She has been a visiting professor at Nara Women's University in Japan and at the University of Havana in Cuba. Sage has been an outside examiner at several universities and has given key speeches at international conferences across the world. She has published 23 books and over 200 articles in international academic journals.