Use a glass of water to create a rainbow inside. Fill a clear glass with water and set it on the sill of a sunny window so that the edge of the glass is just slightly hanging over the side of the sill. Alternatively, you can simply hold the glass in the window. Explain that rainbows occur when light bends. Inform students that when sunlight passes through the water in the glass it will bend. Encourage students to watch for a rainbow to form. Place a piece of white paper on the ground below the rainbow and have students use crayons to "trace" the rainbow onto the paper.
Create models of rainbows with paper plates and crepe paper streamers. Cut paper plates and distribute them to students. Instruct students to use crayons or markers to color their paper plates the colors of the spectrum. Once they have colored their plates, provide them with crepe paper streamers that represent the colors of the rainbow. Have children cut lengths of streamers and tape or glue them to one end of the paper plate, matching the color of the streamer with the color of the marker or crayon. Punch a hole in the top of the paper plate. String a piece of yarn through the hole and tie it in a loop. Hang the paper plate rainbow as a decoration.
Explain to children how light bends in different ways, not just through water. Hold the back of a CD up to a light source and examine the rainbow effect that occurs. Use CDs to create decorative suncatchers. Provide students with CDs, construction paper, markers, glitter glue and any other craft materials you think are appropriate. Instruct them to glue a piece of construction paper onto the label side of the CD and have them cut off any excess paper. Encourage students to use the craft materials to decorate the paper. Poke a small hole through the construction paper that covers that hole in the center of the CD. Thread a piece of filament through the hole and tie it in a loop. Use the filament to hang the craft in a window and watch as the sun's rays are refracted on the back of the CD.
Make rainbows with this unique approach. Sprinkle powdered drink mix on a piece of paper. Offer students a spray bottle filled with water and encourage them to spray water onto the drink mix. As they spray the water, the powder will dissolve, spreading the color out onto the paper. Sprinkle different colors of powdered drink mix onto the paper and spray the water onto it -- the colors will blend together, creating a rainbow effect.