Find what colors were used to create the colors in different markers. Look at each color and decide which colors you think were combined. Cut the fluted section from a coffee filter. Make marks with different colored markers on the filter about two inches from the top, spacing them at least three-fourths of an inch apart. If the filter isn't large enough for all the colors you want to use, then use two filters. Place the filter in a bowl of water, placing the end farthest from the ink in the water. Watch what happens to the colors as the water moves up the filter. Check your hypothesis.
Find out whether you can split white light and form the spectrum. Place black tape around the edges of a small mirror. Put a paper clip through a clip and place the clip on the edge of the mirror. Use a second clip to attach the mirror to the edge of a petri dish half full of water. Angle the mirror. Cut a thin opening near the top of a piece of black oak tag placed lengthwise on the long side. Place the tag board in front of the light source and place a piece of white tag board below the slit. Place the mirror so the light hits the mirror underwater. A rainbow should appear on the white tag board.
Find out what will happen if you blend colored lights. Cover the ends of three paper towel rolls with different colors of cellophane: yellow, red and blue. Place a flashlight through the other end of the paper towels. Lay a piece of white tag board on the floor. Have three people each take one paper towel. Turn on the lights and shine them on the tag board. Intersect the three colors and watch what happens as they overlap.
Try to create white light. Cut a white cardboard circle with a 4-inch circumference. Divide the wheel into eight even sections. Color each section a different color using the colors of the spectrum, in the order they appear: red, orange, yellow, green, blue, indigo and violet. Punch a hole in the center with a sharpened pencil. Spin the pencil and watch the colors blur together.