Neil Challis was born in Cambridge, UK. He studied mathematics at the University of Bristol and subsequently worked for some years as a mathematician in the British Gas Engineering Research Station at Killingworth. Since 1977, he has worked in the Mathematics Group, Sheffield Hallam University, UK and is currently head of that group. He obtained a PhD in mathematics from the University of Sheffield in 1988 and has taught mathematics to a wide variety of students, across the spectrum from first year engineers and other non-mathematicians who need access to mathematical ideas, techniques and thinking, to final year single honours mathematics students. Harry Gretton was born in Leicester, UK. He studied mathematics at the University of Sheffield, obtaining his PhD from there in 1970. He has taught mathematics sciences since then, both at Sheffield University and Sheffield Hallam University, and has been a tutor with the Open University since it was conceived. He has taught many varied students on many varied mathematically-related courses. In recent years he has developed a particular interest in the impact of technology on the way mathematics is taught, practiced and assessed.