To make sure substitute educators are well-prepared to take over my class, I keep a few things ready at all times. I keep a generic schedule for the week, including times for lunch, recess, P.E., art, reading, library, math and any additional duties I have.
Plus, I have a bag of supplies that can be used for some out-of-desk activities like this one: assemble two bags with four or five props (old hat, stuffed animal, pencil, quarter, sunglasses) in each one; divide the class into two groups and ask each to create a short play using all the props in the bag. Each student must have a speaking part in the play. Give each group 15 minutes to create their play. At the end of the time, ask each group to present its play to the rest of the class.