Science Experiment: Water Cycle in a Bag

Water Cycle in a Bag

One of the main components of hydrology that sticks in my mind is the water cycle. Water is amazing! It changes form over and over again. As creatures on this Earth, we observe water in its different forms almost every day. Whether it’s raining or in clouds, moisture on windows, or

pools of water built up. In this activity, we will try to identify the components of the water cycle and observe the water cycle by constructing a simple, miniature model.

Little itty bitty water molecules are always on the move in what is called the water cycle or hydrologic cycle. The heat from the sun causes the water to evaporate and become a vapor. As the water vapor cools down, it condenses, forming tiny droplets that gather to form clouds. Have you seen those before? I told you you’d witness the water cycle every day. As the droplets get larger, they become heavier causing them to fall to the ground as precipitation (like rain, sleet, or, my least favorite, snow). Some of this precipitation joins lakes and streams. This is called surface water. Other times some of it soaks into the ground where it becomes groundwater. The process of water soaking into the ground is called infiltration, or recharge.

Knowing this will help in explaining the process to those who are not familiar or children.

You will need: Clear Plastic Bag (zipper stule, sandwich size), Water (2 Tbsp), Tablespoon, Rubberband or twist-tie, Masking Tape.

  1. Prepare your supplies all together so the process goes quicker and smoother. I’d have a cup of water to the side to make it easier to scoop the water, especially with smaller children.
  2.  Pour 2 tablespoons of water into a clear plastic bag.
  3.  Blow air (not spit) inside the bag with your mouth and quickly seal the bag closed with a rubber band, twist-tie, or zipper-closure. DO NOT POP THE BAG! It may be tempting but it ruins the whole experiment.
  4.  Place the bag on a sunny window ledge or tape directly to the window pane using that masking tape. Duct tape will be too sticky and scotch will not support the weight very well. . Periodically look at the bag throughout the day. What changes do you see? Jot down the results into a notebook.
  5.  For instant results, make two bags. Put cold water in the first bag and hot water in the second bag. Compare the two bags. Again, document the observations in your science journal.