Thirsty Celery Materials: Celery stalk 2 clear glasses red and blue food coloring knife and spoon Method: fill both glasses with water. Stir red into one and blue into the other. Keep adding color until liquids are dark. Slit celery stalk from bottom to just below the leaves. Put one end in the blue and one in the red. Let sit for a few hours until the stalks turn colors. What color is the top? Cut celery in half and look inside. .