Science -- Weather: Fill the cup with water. Put shaving cream on top for a cloud. Explain that when clouds get really heavy with water, it rains! Then put blue food coloring on top of the cloud, and watch it rain. Air and Weather unit
Wonders of Water Science Project - Making Clean Water: After learning about pollution and water conservation, you could have your Brownies split into groups and make clean water that has been "polluted" with dirt and other sediments.