Place a clear plastic lid, rim side up, on top of a flashlight that is turned on. Put several drops of dish detergent on the lid. Add enough water to fill the base of the lid. Use one end of the straw to stir the mixture and the other end to blow rainbow bubbles.
Fill a shallow pan 1/4-full with water and place a mirror on its side at the edge of the pan. Position a lamp or flashlight so light shines directly into the mirror. Hold up a white piece of paper to catch the light's reflection. A rainbow should appear at the edge of the light's reflection.
Pick a dark room with white walls. Fill a glass with water. Place a small mirror inside the glass and tilt the mirror slowly upward. Shine a flashlight or light from a lamp into the mirror. A rainbow will appear on the white wall.
Place the blank side of a CD on a stable surface. Turn off the lights and shine a flashlight onto the CD. With your other hand, hold a white piece of paper so the light reflecting off the CD shines onto it. This will create a rainbow.