I keep a spreadsheet with the names of all the students for each of my classes organized in alphabetical order on my computer. I use this list to assign daily helpers for each class period. The list is posted next to my assignment board where the helpers post assignments, notes, the date, etc. We rotate through the list throughout the year so everyone gets a chance to run errands and do general odd jobs for me. I also write my lesson plans on the computer with all kinds of advice for subs including the names of the daily helpers. I print these out each week so that if I'm gone the sub has all the necessary information at his/her fingertips.