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1. Place a clean dry penny on the tray.
2. Partially fill a dropper/pipette with water. (Note that you take water into the dropper by squeezing the plastic or rubber bulb, placing the tip of the dropper well under the surface of water in a cup, and releasing your squeeze to let water into the dropper. You let drops out of the dropper by gradually squeezing the plastic bulb. Before you begin the experiment practice using the dropper over the cup of water until you can let the drops out only one at a time.)
3. Hold the plastic dropper vertically about 1 centimeter above the penny in order to place drops of water on the penny one by one.
4. You and your team should count the drops carefully as you drop them on the penny. Don't lose count! Watch from the side as the water builds up.