His research interests include developing and evaluating tools for supporting collaborative learning, particularly involving student-generated resources, and exploring the ways that students engage with these environments. One of his projects, PeerWise, hosts more than six million practice questions, with associated solutions and explanations, created by students from 90 countries. He has fostered a community of educational researchers around this project, more than 160 of whom have published their work as a result. Dr Denny has been recognized for contributions to teaching both nationally and internationally, receiving New Zealand's National Tertiary Teaching Excellence Award (2009), the Computing Research and Education Association of Australasia Award for Outstanding Contributions to Teaching (2010), and the QS Reimagine Education Overall Award (2018).