Sleeman began his career as a lecturer in computing at the University of Leeds and co-founded the Computer-Based Learning Unit there in 1969.
This led to his interest in intelligent tutoring systems and an edited volume on that subject with John Seely Brown.
Further, with Mark Musen, Sleeman organized one of the 2008 AAAI Stanford Spring Symposia entitled: Symbiotic relationship between the Semantic Web & Knowledge Engineering.
He was one of the principal investigators of the EPSRC-sponsored IRC in Advanced Knowledge Technologies (2000–2007), and PI of the DTI/Rolls-Royce sponsored IPAS project (2005–2008).
Sleeman has a track record of interdisciplinary research work with education, engineering, science and medicine.