Observe the germination process by planting seeds in different conditions, such as sunlight, darkness, and varying amounts of water, to see how they affect growth.
Build a simple catapult using household items like popsicle sticks, rubber bands, and a spoon, then launch small objects to test its distance and accuracy.
Build a simple water filter using materials like sand, gravel, and activated charcoal to clean dirty water and demonstrate basic filtration principles.