All living things need water, so it is important to keep natural water sources like rivers, lakes, and oceans clean of pollution. Pollution can come in many different forms, so sometimes it is hard to know how "clean" a water source is or where pollution is coming from.

Some forms of pollution are easy to see, such as trash or oil. Even dirt can be considered pollution if too much gets into the water supply and turns the water muddy. Other forms of pollution, like chemicals, might require scientific tests to find.

Nature has different ways of helping keep the planet's water clean. The water cycle uses the heat of the sun to take water from the surface of the Earth up into the air in tiny droplets. These droplets are so small that many visible forms of pollution are left behind. When the droplets cool, they form clouds and fall back to Earth as rain, collecting in rivers, lakes, and oceans again. 

Use this activity guide to learn more and explore the topic of water quality, including building your own mini water cycle! This activity guide can be used in school, at camp, at a park, or even at home. With activities to do both on and off the worksheet, it's perfect for your next environmental investigation.