I keep a stack of these forms in my class, printed on lime green paper, right by my homework turn-in bin. If a student doesn't have their homework done, they fill out the form and submit it in place of the assignment. I keep all of the forms in my class binder for conferences, etc. It helps to have the students' excuses right there in their own handwriting when talking to parents about their grades. It also eliminates students' later claiming, "I know I turned that in..."