I use songs, music on CD's to clean up too, they get a 5 minute warning before clean up time as well. Nursery Rhyymes work to as well as simple questions. I also start circle when I have some there and then as they clean up or do what ever they just join in. Transitions are a part of the day like anything else and it can be a learning experience, although they are more limited- my children are kept so busy they dont have to wait unecessarlily for much. It comes so natural as to what to do it is hard to explain.