Water Cycle in a Bag      Create a closed system in order to observe the water cycle.      Ziplock bag Permanent markers Sand Perlite (can be replaced with potting soil) Grass seeds (or other quick growing seeds) Soda bottle cap Water Sunny window      1. Mix even amounts of sand and perlite – enough to fill the bottom inch of the ziplock bag. 2. Add a small amount of seeds. For grass seeds -2 soda bottle caps, for beans 2-5 seeds. 3. Add a small amount of water, enough to make your soil mix moist, not drenched. 4. Seal the bag. 5. Use the permanent markers to draw a landscape to your bag. Mark the top of the soil, draw some clouds, sun, plants, etc. 6. Tape the bag to a sunny window.      Water is one of the basic building blocks of all life. It is also one of the basic ingredients of our weather. About 71% of the Earth's surface is covered by water. It is present in oceans, rivers, lakes, the polar ice caps, clouds, rain or snow, ground water and living things such as plants and animals. Water molecules are constantly on the move in what is called the water cycle (or hydrologic cycle). Heat from the sun causes the water to evaporate and become a vapor. As the water vapor cools, it condenses, forming tiny droplets, which gather to form clouds. As the droplets get larger, they become heavier causing them to fall to the ground as precipitation (like rain, sleet, or snow). Some of this precipitation joins lakes and streams (called surface water), and some of it soaks into the ground where it becomes groundwater. The process of water soaking into the ground is called infiltration, or recharge.      For Older Children Have the participants experiment with the temperature of the water and observe what affects it might have. Set up two bags with soil and seeds. In one bag add cold water and in the other add hot water. Place both bags by a sunny window making sure that they get equal amounts of light. Observe what happens.      http://www.kidzone.ws/water/ http://kids.earth.nasa.gov/droplet.html