I frequently have students absent, leaving my room for music lessons, calls to the office, nurse, etc. I have a box in my room labeled extra copies. After I pass out worksheets, I put 10 extra copies in the box for students to use. When a student comes back to my room and notices we are working on a sheet he/she doesn't have, they know to go to the extra copy box and get the sheet. I post all assignments on my backboard so they could check to see what they missed and do not have. I leave the assignments up for two weeks. This has eliminated them interrupting class to ask for a worksheet and makes them responsible for catching up on work they missed. Frequently students may ask to recopy a worksheet because it is sloppy and they want to do it over, I just tell them to go to the box and get another copy. This also instills pride in their work.