Start with a jar or vase filled with clear water. I labeled the vase, "US".
Next, take the food colorings, which I labeled, "SINS" and talk to the youth, etc about what are some sins we commit? With each sin stated, add a drop of food coloring to the clear water. After quite a few sins have been added, the water will look dirty ( like we do to our lives when we sin ).
Then talk about the atonement and repentance and then pour the bleach, labeled, "ATONEMENT" into the vase of dirty water. You probably will have to stir the water, but it will clear up and be "clean" like before.