Have the kids bring an un-crushed cardboard tube from a roll of paper towels. These are 11 inches long and 1 5/8 inches in diameter. Provide a salad dish full of colored and clear plastic beads. Provide transparent plastic document covers. Provide Scotch tape, construction paper, scissors and a document single-hole punch. In preparation for class, go to the local hardware or home improvement store and purchase lightweight mirror glass. Have the store cut the glass into sections that are 10 1/2 inches long and 1 3/8 inches wide. Make enough for each student to have three.
If students are too young to safely work with the mirror sections, the teacher can prepare the mirrors in advance of class. Lay a towel over the work surface in either case to prevent the mirror sections from breaking in the event of mishaps. Lay the mirror sections out side-by-side, lengthwise, facing up, and tightly together. Tape the three sections together lengthwise with a strip of tape along each joint. Fold the end sections up until they meet, forming a peak. Tape that joint from the outside, then tape all joints from the outside. The reflective surfaces should face inward now with the sections making a triangle as seen from the ends. Tape the outside liberally to cover sharp edges and ensure the mirror tube is sturdy.
Have the kids cut a section of clear document protector large enough to cover the end of the paper towel tube. Place the clear plastic over one end of the tube and tape the edges to the outside of the tube, creating a clear window over one end. Make a roll of construction paper that wraps around the the tube, extending the tube by about 3 inches past the clear window end. Tape the construction paper down around the tube. The construction paper will wrap around the tube more than once, and that is fine. It is stronger. Now you have a 3-inch-deep "cup" on one end of the tube. Fill that cup two-thirds full with colored beads. Then tape another clear plastic window made out of document protector material to the end of the cup, sealing the beads inside.
Have the kids slide the three-sided, inward-facing mirrors into the open end of the tube. The mirror assembly will fit snugly without warping the tube. The mirror assembly is one-half inch shorter than the tube, so they can slide the mirrors in until the reach the first plastic window in the color vault, and there will be a half-inch clearance on the open end. Cut a piece of construction paper into a 2-inch circle. With the hole punch, make a hole dead center in the circle. Center the hole over the open end of the tube, then fold the edges down around the outside of the tube and tape them firmly. The kaleidoscope is finished. Have them aim it at the light and look through, watching the designs change as the roll it.