Plant life that covers the ground helps keep soil from eroding when rain water moves over it. Cut a 1-inch thick, 1-foot square piece of soil that has thick grass growing on it. Place it on a 1-foot square piece of plywood. Similarly, cut a 1-inch thick, 1-foot square section of soil that does not have any vegetation growing on it and place it on a piece of plywood. Using a 2-by-4 piece of lumber, position the board so that it is sitting on its thinnest side. Set one end of each of the plywood pieces on the 2-by-4 lumber to create ramps. Place a cookie baking tray with a lip around the edge at the bottom of each piece of plywood. Fill a large pitcher with water. Slowly pour out the water near the top of the grass-covered piece. The cookie try will catch any soil that erodes. Refill the pitcher and do the same with the soil-only piece. Observe the amount of soil particles collected in each tray.
Make observations to see if tree leaves are waterproof. When a rain storm begins, place your hands on the ground underneath a large tree that has broad leaves. Feel the ground in an adjacent area that is out in the open. Observe that the area under the tree takes more time to feel as wet as the ground in the open area. After the storm has passed, compare the amount of moisture in the ground under the tree to that in an adjacent open area. Use a small garden hand shovel and see how far down the rain water has seeped. Of course, do not go outside in a rain storm if lightning is present.
Tides are caused by the gravitational pull of the moon. The moon goes through phases during its orbit around the earth. Generally, these phases are called new moon (completely dark), waxing crescent, first quarter, waxing gibbous, full moon (completely illuminated), waning gibbous, last quarter and waning crescent. This completes one full cycle. Determine if the phase of the moon affects the height of tides. Locate a bulkhead in a bay that you can safely access at high tide. Use a local tide table to determine the daily time of high tide. Use a ruler or yardstick to measure the distance from the top of the bulkhead to the top of the water at high tide. Do this daily through a complete moon cycle, which is about 29-1/2 days. Record your daily measurements and compare them to the phases of the moon. For safety, always have another person with you when you are around the bay.
A siphon moves water from one location to another. Stack several thick books on a table. Fill a 2-liter plastic soda bottle with water and set it on top of the stack of books. Place another empty bottle 2 feet from it, but down on the table - not on the book stack. Insert one end of a plastic tube, such as the kind used for fish aquariums, into the open top of the water-filled bottle. Suck on the other end of the tube to draw water through the tube. Once water comes through, place the end of the tube into the lower bottle. The water will continue to flow from the full bottle to the empty bottle.