Give your zen garden an upgrade with Sandscript. This device uses magnets to let you control a ball with three dials, tracing patterns in the sand. You can make symmetrical mandala patterns or randomized doodles on command.
34 Unexpected Ways Coffee Grounds Can Make Your Life Better
make your own fossils (dinosaurs, shells, etc.) 1 cup used coffee grounds cup cold coffee cup salt 1 cup flour 200 for 30 min, cool on one side then flip and dry on counter overnight (or make snicker doodle cookies with prints and EAT the fossils)
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.