Water is essential for all life on Earth. Every living thing -- plants, animals, and people -- needs water to survive. People use water for drinking, cooking, cleaning, and growing food. Water shapes the land through rivers and rain. Most of Earth's water is salty ocean water; only a small amount is the freshwater that people and most land animals can use. Because freshwater is limited, it is important to use it wisely and not waste it.
Track classroom water use for a day. Discuss how water is used at home (drinking, cooking, bathing, watering plants). Compare freshwater and saltwater quantities using a visual (a gallon jug for all water, an eyedropper for freshwater). Discuss what would happen if you had no water for a day. Connect water use to the water cycle -- where does tap water come from?
Think about your day so far. You probably drank some water, washed your hands, maybe flushed a toilet or had food that was cooked with water. Water is so common in our lives that we rarely think about it. But water is the single most important substance for life on Earth, and understanding why helps us treat it with the respect it deserves.
Every living thing needs water. Plants drink water through their roots and use it to make food from sunlight. Without water, plants wilt and die within days. Animals drink water to keep their bodies working -- it helps digest food, carry nutrients through the body, and cool down on hot days. People are no different. Our bodies are about 60% water, and we need to drink water every day to stay healthy. Without any water at all, a person can only survive for a few days.
Here is a surprising fact: even though Earth is covered in water, most of it is not the kind we can use. About 97% of Earth's water is salty ocean water. You cannot drink saltwater or use it to water crops. Of the remaining 3% that is freshwater, most is locked up in ice caps and glaciers at the North and South Poles. That leaves less than 1% of all Earth's water available in rivers, lakes, and underground sources that people can actually use. One percent does not sound like much -- because it is not.
That is why it matters to use water wisely. Turning off the faucet while brushing your teeth, fixing leaky pipes, and not wasting water all help make sure there is enough for everyone. The water we have is recycled through the water cycle -- the same water evaporates, falls as rain, and flows through rivers over and over. But the total amount does not increase. What we have now is all we will ever have, and every person, animal, and plant on Earth is sharing it.
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