Why are there clouds in the sky? Where does rain come from? With the water cycle in a bag experiment, you can answer your kids’ questions and satisfy their curiosity about the water cycle.
STEM concept: Water cycle
• ziplock bag
• permanent marker
• blue food coloring
• clear tape
Steps to follow
1. Use colored markers to draw a sky on the upper half of your ziplock bag. Include clouds and the sun.
2. Fill a cup with water and add a few drops of blue food coloring.
3. Pour the blue-colored water into the bag and zip it tightly so no water escapes.
4. Using some clear tape, hang the bag outside or on a sunny window.
5. Check the bag after a couple of hours. You can also check again the next day. You will eventually start to see drops of water sticking to the side of the bag. Some will be in the “clouds” and other drops will be coming down like rain.
The science behind the experiment
After a couple of hours, you will be able to observe some water droplets rising and sticking to the sides of the bag. Eventually, these droplets will fall back down to the pool of water at the bottom of the bag, just like how the water cycle happens in nature.
The water cycle starts with Earth’s water like those in lakes, seas, rivers, and underground. Because of the sun’s heat, water is changed into vapor and rises into the atmosphere in a process called evaporation.
After the warm water vapor evaporates, it starts to cool down and change back to liquid. They begin to form clouds. This process is called condensation.
When the clouds get too heavy with water droplets, it begins to rain or snow. Water falls back down to Earth in a process called precipitation.
Learning about the water cycle in a unique way like this can make kids appreciate the value of this precious resource even more!