Remove the labels from the soda bottle. Mark a black line around the bottle 1 inch below the shoulder. Use the craft knife to carefully cut around the line to separate the neck from the body of the bottle.
Pour the boiling water into the jug, add the gelatin powder, and mix well until the gelatin has dissolved. Pour the liquid into the bottle so that the feet are full and there is a level line of gelatin just above the feet. Set aside to cool and become solid.
Remove the lid of the bottle and turn the neck upside down so it forms a funnel. Place it in the body, and secure it with scotch tape.
Mark a black line around the top edge of the gelatin to form the baseline. Make a mark every 1/4 inch on the side of the bottle using the ruler. This will be your scale to measure rainfall.
Place your completed rain gauge in an open area, away from buildings and trees. At the same time each day record the amount of rain collected; 1 inch of rain in your gauge is approximately 25 quarts of water per square yard.