Here are the courses I've been working on this year:
Here are some other things I do which have some presence on the internet:
I have a personal home page.
As a hobby, I am heavily involved in various activities of the UK Mathematics Trust, and have helped organise and run many hard mathematics competitions, of several different sorts, for school students.
My default email address for business related to Sheffield is J.D.Cranch@sheffield.ac.uk. My office is G39c, in the Hicks Building. My postal address at work is
School of Mathematics and Statistics
University of Sheffield
G39c, The Hicks Building
My office telephone number is 0114 2223788 (from within the United Kingdom).