While you try to recall your 10th-grade chemistry class, your child will simply be doing this spectacular project, which demonstrates the movement of molecules, given the right solvent. And it passes the cool-learning litmus test with flying colors (like all the projects at stevespanglerscience.com, from which this one was adapted and published recently in Wondertime magazine).
Newspaper (another use for the Reflector!)
1 clean white cotton T-shirt
Plastic cup (8 to 12 ounces)
Plastic water-bottle cap
Permanent markers (such as Sharpies) in various colors
1. Cover your work surface with newspaper: Choose a picnic table outdoors (ideal), or a spot indoors near an open window, as the alcohol can be fumey. (It's flammable, too, so stay away from heat sources.)
2. Lay the T-shirt flat on the work surface, then slip the cup inside the shirt from the bottom, standing the cup upright in the place you'd like to start decorating. Stretch the rubber band over the T-shirt and the rim of the cup, pulling the T-shirt taut.
3. Put the bottle cap in the center of the stretched fabric. Have your child use a marker to make a circle of dots around the bottle cap, keeping the dots fairly close to the cap.
4. Remove the bottle cap. Using the eyedropper, slowly squeeze 20 drops of rubbing alcohol onto the blank spot where the cap was. (Supervise closely or do this part yourself; the alcohol can sting and is dangerous if ingested.) As the fabric absorbs the alcohol, the ink will spread outward in a circular pattern like fireworks. Allow the design to dry for 5 minutes before repeating on a new area of the shirt.
5. Experiment with different shapes a dotted star, a heart, or concentric rings of dots. To make flowers, when the designs are dry, slip some paper towels inside the shirt and draw stems with markers.
6. When the shirt is done and completely dry, pop it in the dryer for 20 minutes to set the colors, then wash and dry as usual.