In August 1994 I participated in a CSEP workshop at the Cornell Theory Centre. I discovered that many people have ideas similar to mine, that new exciting tools are being created, and that good teaching is good teaching, no matter what the medium used. Inspired by this workshop, I have been thinking about what a good on-line teaching document should look like. One of my first tries is our Introduction to physica - an on-line tutorial on using a popular software package. Our students typically go through this tutorial during one of the first laboratory sessions in their Year 2 Classical Mechanics lab.