Your child will create a model of the water cycle as they observe and identify the pattern of continuous movement of water in the air and on Earth.
Learning Area(s): Reading and Writing; Science
- 2 sandwich-size zip-top bags
- black permanent marker
- duct tape
- 2 small cups
- water (room temperature or warm)
- food coloring (optional)
- journal, notebook, or a few sheets of paper stapled together
Before the activity:
- Locate a window that gets full sunlight.
- Cut a piece of duct tape slightly longer than the top of the plastic bag and set it aside.
- Read through the Tips section for possible problems that might arise.
- Pour two tablespoons of plain water into a second cup.
- If using food coloring, mix ¼ cup of water with two drops of food coloring in a cup and set aside.
Begin by taking your child outside on a warm, sunny day. “Let’s talk about how water moves through the water cycle.” Pour the two tablespoons of plain water on the pavement. “If we wait here long enough, this water is going to move. Do you know where it will go?” Allow your child to respond. Explain that the water will move into the air by evaporation and then continue its journey through the water cycle. “Let’s go inside and talk about what evaporation means and how water moves through the water cycle. We will make a model of the water cycle with a plastic sandwich bag.”
Once back inside, use the diagram of the water cycle as a guide as you and your child each draw it on a bag with a permanent marker. As your child creates a model of the water cycle, you will create one alongside your child.
Start by drawing the Sun in the top left corner and a wavy line across the bottom to represent a body of water. Write the word water in the lower left corner below the water line.
Explain: “The water cycle needs the Sun’s energy to heat the water. Evaporation happens when the water heats up and turns into a warm gas called water vapor, which rises into the air.” Draw wavy lines rising from the water and label them evaporation. “Have you ever seen steam above a boiling pot of water? That’s an example of water vapor and evaporation at home.
“As the warm water vapor rises high into the cold air that surrounds Earth (atmosphere), it cools. That’s when condensation forms. This means the gas turns back into liquid in the form of very tiny droplets of water. We cannot see the droplets until thousands of them come together and form clouds.” Draw a cloud and write condensation inside the cloud. “An example of condensation is when water droplets form on the outside of a cold glass of water. Can you think of another example of condensation?” Other examples include water droplets on a window, a foggy mirror after a hot shower, or dew on the grass in the morning.
“The water droplets join and become bigger and bigger until they are too heavy to float in the air. Then, they fall back to the Earth as precipitation. Precipitation is rain, sleet, hail, and snow.” Draw drops of water falling from the cloud and label them precipitation.
“Finally, the precipitation joins a larger body of water like a lake or ocean. This is called collection.” Write collection in the bottom right corner, below the water line.
“Our water cycle models are almost ready!”
- Pour half of the colored water into your child’s bag without letting it splash the sides of the bag. (Droplets that splash on the sides of the bag could be misinterpreted as condensation or precipitation.)
- Gently seal the bag without shaking it.
- Use duct tape to carefully secure the bag to the outside of a sunny window.
- Repeat with the other half of the water in the second bag.
Ask your child to create a hypothesis, or guess, by completing the statement below in their journal: If water is left inside a bag for 24 hours, the water in the bag will…
Ask and discuss additional questions, and allow them to write predictions in their journal.
- “Why do you think it’s called the water cycle?” (It happens over and over.)
- “Why do you think we placed the water cycle model in a sunny window?”
- “Do you think all of the water in the bag will evaporate? Why or why not?”
- “Where do you see the condensation in the bag? How is that similar to/different from what happens in the air?” (Clouds)
- “How could you speed up precipitation inside the bag?” (Gently push the side of the bag so water droplets join together and become heavy enough to run down the bag.)
- “What do you think will happen inside the bag overnight?”
- “What do you think is the most important part of the water cycle? Why do you think so?” (Your child might say the Sun because it provides the heat to cause evaporation, which leads to the other parts of the cycle. An alternative answer could be the water because the cycle can’t begin without something to evaporate.)
Have your child check the bag every three hours and record their observations in their journal.
- Consider warming up the water before you pour it into the bag so your child can see changes more quickly.
- If the bag is not showing signs of condensation after a couple of hours, you may want to carefully move the bag to a fence that gets full sun. If you have a chainlink fence, you can use clothespins or chip clips to secure the bag. If you have a wooden fence, attach the bag by placing a strip of duct tape across the top of the bag just below the zip seal. Hold the bag in place as you secure it with three push pins placed evenly across the tape. The tape helps keep out air so that condensation can form and prevents the pin from tearing a hole in the bag.
- You can remove the sticky residue from the tape off of your window with some rubbing alcohol.
- If you have single-pane windows or doors, you can attach the bag to the inside of the window. Condensation is unlikely to form if you have double-pane windows.
- To learn more about the water cycle, explore some of these books:
- Drop: An Adventure Through the Water Cycle by Emily Kate Moon
- The Great Big Water Cycle Adventure by Kay Barnham
- The Snowflake: A Water Cycle by Neil Waldman
- Agent H2O Rides the Water Cycle by Rita Goldner