Things required: A plastic tray, plaster of Paris/ plasticine, sponge or a piece of cloth, and a stick Spread a layer of plaster of Paris (mixed to thick consistency)/ plasticine in one half of the tray. This represents the land, and the other half the ocean. Shape the plaster so that it slopes gently. Make some grooves on the slope. These represent rivers. Let the plaster dry. Pour some water on the land. The water flows directly into the oceans. Put some sponge or cloth across the edge of the plaster of Paris. This represents the wetlands between the dry land and the ocean. Now pour some water slowly onto the land. Observe that the sponge absorbs the water. Keep pouring the water. Notice that only excess water flows into the oceans. A wetland, like the sponge in this activity, holds large amounts of water and helps prevents floods. In its other function, a wetland acts as water storage and makes water available by releasing it slowly.