"What basic supplies should be in every art cupboard?"
Paper. Lots of paper: every size, every shape. You can use photocopy paper, newsprint, mural paper, and butcher paper. Even paper grocery bags cut up into squares will do just fine as will old shirt and cereal boxes.
Pencils. If nothing else, you must have pencils. Nice big fat pencils for little hands and smaller pencils for your "grown up" students.
Crayons. The brighter your crayons are, the better.
Markers. Make sure they are washable for the little ones.
Modeling Material. This can be clay, or even homemade goop—anything that can be formed. We love Crayola Model Magic.
Pastels. Try to have both chalk and oil pastels on hand. Chalk pastels should be reserved for your older students while the oil pastels can be introduced to the younger set. Sakura makes a terrific oil pastel.
Scissors. Provide safety scissors and adult assistance for the tiny ones.
Glue. Just a small container of glue is all you need, or you can make your own with flour and water.
Paint & Brushes. You will be most pleased with water-base paints (tempera or watercolor) and brushes from small (¼") to large (1"). Here's a tip: Make clean up easier by adding a few drops of dish soap to your paints.
Found Objects. You can use buttons, beads, stamps, thread, and so on in many an art project.
Art and craft time in your childcare program can be fun, educational, and result in treasures that are saved (and displayed on refrigerators) for years. But some art supplies and art activities can be unsafe unless caregivers follow simple guidelines for selecting and storing materials and teach children how to use them properly. Scott G. Allen, Executive Director, Illinois Chapter, American Academy of Pediatrics has provided us with some helpful tips. You can find those here: http://www.kinderart.com/teachers/artmaterialsafety.shtml