Using a glass bowl of tap water with an empty glass container inside the bowl, your sixth grade student can demonstrate how sunlight evaporates water that later condenses into rain. The small, cellophane-covered habitat demonstrates evaporation, precipitation and different water storage methods in the cycle. Alternately, the student can add salt water to the glass bowl to demonstrate how the water cycle evaporates salt water to rain fresh water on the land -- the empty bowl sitting in the salt water.
Posters, dioramas or computer-generated demonstrations are good options for demonstrating the water cycle. The sixth-grade student can explain and illustrates evaporation, condensation, filtration, transpiration, precipitation, percolation, water storage and run off. Each step in the process completes a vital step in how our planet stays hydrated. The illustration shows how plants, sunlight, bodies of water and land masses keep the cycle moving. It also demonstrates how the largest concentration of water, salt water, continues to feed plants, animals and humans without the need for expensive and complicated filtration systems to remove the salt.
Filtering pollutants out of the ground water keeps the water safe to drink; plants play a vital role in this filtration system. Using an experiment disseminated by the Environmental Protection Agency, sixth grade students can use six common potted plants to filter water contaminated by soil, vegetable oil, powdered drink mix, powdered and liquid household cleaners. Students watch as each substance, mixed in water, is poured into a pot; then, they can observe how the soil and plant filter the substance. Sixth grade students should research and understand the dangers and benefits of using plants and soil to create safe drinking water.
When rain water becomes polluted with contaminants that create acid rain instead of pure water, it affects how plants grow. Discuss different pollutants that create acid rain such as sulfur dioxide and nitrogen oxides released by power plants and automobile exhausts. Students can create projects to demonstrate the effects of acid rain by utilizing three plants and three plastic bags with alfalfa seeds on cotton batting or moist newspaper. Water one plant and one baggie with filtered tap water, another set with one-half cup of vinegar diluted with a cup of water and the final set using 100-percent vinegar. Observe how the healthy plants respond and whether the seeds sprout. Alternatively, compare the acid rain levels in your area to control water. Water one set of plants and seeds with filtered tap water and another set with captured rain water. Compare your plants and seeds watered with captured rain water to similar plants watered with diluted and full strength vinegar.