As art teachers we often have very little time to transition between classes, so clean-up the kids can do themselves is a blessing!! This year, whenever we were using paint or glue, I put out a dampened sponge at each table. Even the youngest of students (kindergarten) delighted in using the sponge to help out. The only warning I gave them was, "Please don't dip the sponge in the dirty paint water -- it already has enough water in it!" At the end of the day I would give all the sponges a quick rinse and they were ready to go for next time.
When we were doing collages or anything that involved cut paper, I put a large size Cool Whip-type container in the center of each work area as the "scrap pile." At the end of each class, a volunteer from the table would empty the scrap bowl into our classroom recycle bin while others at the table gave the floor a quick pick up. Now, that was easy clean up!