A challenge to suit your Unit (clean drinking water)
Clean drinking water is vital for everyone but not accessible to everyone. This activity allows the Brownies to experiment to see if they can produce clean water. Point out to Brownies that even if their water looks clean, there are things they can’t see that might make it unsafe to drink. When in doubt, boil water before consuming.
• Cut the plastic bottle in two and turn the spout end into the wide end. This is your filtration unit.
• Layer the filter materials in the spout and then put through your dirty water.
• Does it filter it?
Allow the Brownies to choose their own materials for their filter from the list above – although you may need to point out the need to pick a material for the outlet that will stay put.
See the effects of layering the materials in different orders – does it make them more or less effective?
Discuss 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