Learn about the weather (The Water Cycle)
Sealable clear sandwich bag
• Write descriptions on the bag as shown in the illustration
• Place coloured water in the bag & seal (make sure you leave some air in the bag to represent the air we breathe)
• Let the Brownies take the bag home and tape it to a sunny window.
• Watch the water cycle at work
Discuss how water is continuously recycled and the importance of having clean water. Over 70% of our Earth's surface is covered by water. Although water is seemingly abundant; the real issue is the amount of fresh water available. 97.5% of all water on Earth is salt water, leaving only 2.5% as fresh water. Nearly 70% of that fresh water is frozen in the icecaps of Antarctica and Greenland; most of the remainder is present as soil moisture, or lays deep underground not accessible to human use.
Only 1% of the world's fresh water is accessible for direct human uses. This is the water found in lakes, rivers, reservoirs and those underground sources that are shallow enough to be tapped at an affordable cost. Only this amount is regularly renewed by rain and snowfall, and is therefore available on a sustainable basis.
The water from the bag represents a body of water (river, ocean, lake, etc.) and evaporates into the bag due to the heat from the sun. The vapour then collects to form clouds during condensation. This is represented by the water droplets on our plastic bag. The droplets then drip down the side of the bag and collect at the bottom due to gravity and the weight of the droplets. This represents precipitation, which can be in the form of rain, snow, hail, etc. The water will then evaporate again to continue the cycle.