Raindrop Race: Use a 12" x 18" sheet of Plexiglas, eyedroppers, baby food jars, and a dishpan. Lean the Plexiglas in the dishpan. Place the dishpan on a tray with two jars of colored water, yellow and blue, and the eyedroppers. Have the children use the eyedroppers to hold raindrop races down the Plexiglas sheet. They will notice that the water slowly turns green in the bottom of the dishpan. Why? Other questions: Which color won, blue or yellow? How many drops did you drop? How fast did your drops go down the sheet?