Choose one material at a time. Test each material five times. Then measure the time it takes to sink to the bottom. Repeat step 2 with the other materials. Design a basic data table to keep track of your materials and times.
Some plankton produces oil and store it in their bodies.
Try folding some material so it will hold about a teaspoon of oil. Determine how this affects flotation. Obtain a leg of nylon panty hose, a wire hanger, string, a rubber band, and a small jar. Place the jar in the toe of the pantyhose. Keep it in place by tying it or placing the rubber band around the lip of the jar.