If you are a Casual Relief Teacher and you really want to get a call back to that school then you need to leave an impression. Leave professional looking notes for the classroom teacher to come back to, they will be impressed with the effort you have gone to. It looks much nicer than leaving your notes on a scrap piece of paper.
There a few variations to the 'While you were out' template. Pick and choose which one suits you best. Print of a few and carry them around to schools with you.
These are also great if you are a classroom teacher and you would like a CRT to leave detailed note for you to return to. Have a stack of these in a CRT folder and you will always be left with notes!