Understanding the water cycle comes with understanding the effect of temperature on the phases of water. Observe the solid, liquid and gas phases of water. Place an ice cube from the freezer in a glass and observe how long it takes for the warmth of the room to change the solid ice into liquid water. Use a marker to mark how much water the glass holds before setting it in a sunny spot. The next day, check to see how much water evaporated when warmed by the sun. With an adult's help, heat the remaining water in a tea kettle and watch as the heat turns the liquid water into steam.
This project requires at least two sets of hands and adult supervision. Fill a pot with water and fill a heat-resistant bowl with ice. Boil the water in the pot. Once the water boils, hold the bowl of ice over the pot, allowing the steam to touch the bottom of the bowl. Use oven mitts as you hold the bowl to avoid getting burned by the steam. When water droplets begin to gather on the outside of the bowl of ice, have a second person hold a pie tin under the bowl to collect the water that falls. After a few minutes, end the experiment and write down what you saw. Compare this process to the process of rainfall, explaining how the water falling from the bottom of the bowl compares to precipitation.
Use colored water to observe the process of evaporation. Put a cup of water into a clear plastic sandwich bag and add a couple drops of food coloring. Seal the bag well and securely tape it to a window while the sun shines through the window. Use a thermometer to measure the temperature of the bag and its contents by pressing the bulb of the thermometer against the outside of the bag for approximately three minutes. Leave the bag hanging in the window for two or three hours. Return to the bag and write down your observations. Look for water droplets on the outside of the bag. Measure its temperature again and write down any change.
Make a small model of the water cycle using a glass jar with a metal lid, ice cubes and hot water. Pour around 2 centimeters of water into the jar. Place the lid upside down on top of the jar, covering up the entire opening, and put three ice cubes on top of the lid and inside its rim. Watch the jar for 10 minutes and write down anything you see. After the 10 minutes end, carefully take the lid off and examine the underside. Write down those observations, as well.