Mosaics are made by pressing small pieces of glass, stone, pottery or other objects into wet cement or plaster, which hardens to become permanent works of art. Since ancient Greek and Roman times, artists have made use of these durable and multicolored designs to decorate floors, walls, domes and even entire buildings with beautiful images--from intricate biblical scenes to colorful geometric patterns.

MATERIALS

Plastic container (cottage cheese or margarine containers work well)
Pencil and paper
Mosaic tiles (available at craft stores) or colored beads, buttons, marbles, stones or dry beans
Plaster of paris
Water
Large plastic bucket
Paint stirrer or long-handled spoon

First, your child should turn her plastic container upside down and trace its circumference onto a piece of paper. This will give her a blank canvas on which to practice laying out her design. Then, she can sort through her mosaic pieces and select enough to arrange onto the traced area. Whether she arranges the pieces into a geometric pattern or a realistic picture, encourage her to stick with a simple design so she will be able to work quickly with the drying plaster. When she is pleased with the arrangement, she can carefully set it aside.

Help your child stir the plaster and water together in a large bucket, following the directions on the box of plaster. It is best to make the mixture a little more watery than directed so the plaster will take longer to dry. Fill up the plastic container halfway with the prepared plaster. This is a crucial measurement: pouring less than half can produce a mosaic that is too weak to be removed from the container; pouring more than half can result in a mosaic whose design is overwhelmed by too much plaster.

You and your child should test the consistency of the drying plaster by lightly touching it every two minutes. She can begin arranging the design when the plaster feels like soft clay. Starting at the center of the container, she should gently press the first piece into the plaster, then continue until the mosaic design is complete (encourage her to work as quickly as possible because the plaster dries rapidly).

Let the plaster dry completely for at least one hour before trying to remove it from the mold. Help your child gently pull the sides of the container away from the plaster. (If you notice cracking, then the plaster has not dried and needs a little longer to set.) Using the balls of her fingers, she can carefully loosen the mosaic by pushing up on the bottom of the container. Place a soft rag on top of the mosaic to provide cushioning, then gently flip it upside down. The finished mosaic will make a beautiful paperweight or coffee table decoration. For a quicker project, try making a paper mosaic by cutting and gluing colored paper "tiles" onto a paper background in a contrasting color.

(Ages seven and up)