What Is Water Cycle?
Water cycle is also known as hydrologic cycle or hydrological cycle. It describes how water moves continuously on Earth.
Water loops through different stages – evaporation, condensation, precipitation and flow. It then goes back to the evaporation stage. The whole cycle starts all over again and hence the name “water cycle”.
For teachers and homeschoolers, here is a very helpful teaching aid — water cycle chart.
This 17″ x 22″ water cycle charts is a great visual learning resource in the classroom and homeschool.
The layout is simple and clear. The colorful illustration is easy to understand. It is printed on quality paper, perfect as a durable wall poster!
Stages Of The Water Cycle
Water covers 70% of the Earth’s surface and makes up approximately 60% of our bodies. This amazing natural resource is essential for life in both animals and plants.
Besides having many amazing properties, water is the only substance that appears on Earth naturally in all three physical states of matter — gas (water vapor), liquid (water), and solid (snow, ice). Most other substances only exist in one state in nature.
As water goes through the different stages of the water cycle, it changes from one form to anther by absorbing or releasing heat energy in the process.
Evaporation takes place wherever there is exposed water, e.g. on the surface of the ocean, rivers or lakes, when we sweat, when animals sweat and when plants transpire.
When the sun heats up exposed water, the water on the surface turns into vapor and goes into the air.
Evaporation can happen at any temperature, but warm water evaporates faster than cold water. If you boil the water, you can see steam rising from the surface. That is a fast, visible evaporation.
Even when you cannot see steam or vapor, evaporation can still be happening although at a much slower rate. You can try this Evaporation –> Distillation experiment to see how water can evaporate even at room temperature.
When water vapors in the air rise and reach the upper atmosphere, the cold temperature causes them to release heat and change back into liquid. These fine water droplets hang on dust particles in the air to form clouds.
In this Can You Make Rain experiment, condensation takes place on the bottle’s wall to form water droplets. This is a very neat experiment and also a water cycle all by itself.
As water droplets collide and condense together in the upper atmosphere, they grow larger and heavier. When the water droplets’ fall speed exceeds the cloud updraft speed, they fall out of the cloud as precipitation in the form of rain, freezing rain, sleet, snow or hail.
Through precipitation, water falls back onto the Earth’s surface.
Some water flows downward and ends up in the sea, lakes or rivers. Some soaks into the ground and becomes ground water, which feeds the plants or runs through the soil ending up in the ocean. Some is consumed by animals.
From there, the water cycle starts all over again.
Simple Water Cycle In A Bag Experiment
In this simple “water cycle in a bag” experiment, we will observe the different stages of the water cycle process up close.
What you need
- Warm up the water until steam starts to rise but do not let it boil.
- Add blue food coloring into the water to represent ocean water.
- Pour the water into a ziplock bag and zip it up.
- Hang the bag upright on the window (or the door like I did) using packing tape.
- As the water evaporates, vapors rise and condense at the top of the bag. A white patch can be seen resembling clouds in the upper atmosphere.
- After a while, water droplets appear on the inside of the bag. As they become bigger, they will eventually slide downward. The sliding down resembles the flow stage that brings water back into the sea.
- If the water is still warm or if the bag is left on the window facing sunlight, it will keep cycling through the four different stages of the water cycle.
Explore more about the water cycle by answering these questions.
- Can you describe the relationship between the water cycle and living things?
- How does snow fit into the water cycle process?
- What causes soil erosion?
- Have you seen the four stages of the water cycle appear in our daily lives?
Water Cycle Teaching Materials
Here are some great tool and books on water cycle and other interesting water facts.
This science workbook is designed for 2nd graders using vocabulary they can understand. The exercises walk you through each stage of the water cycle.
This workbook is excellent for self-paced learning.
This is a more substantial 3D water cycle model for the classroom.
This model includes a set of 10 full-color study cards to illustrate the process.
You need to supply your own ice cubes, water and heat lamp for the demonstration.
It is nice to use this bigger model of the water cycle to demonstrate to the class.
This is one of my favorite books on the water cycle process.
It is a beautifully illustrated picture book, but despite that, this is a non-fiction book.
It follows a snowflake through the seasons to see how water freezes during the winter and then melts when spring arrives.
Once it’s in liquid form, it goes through the four stages of the water cycle.
The best part of this book is that it teaches children how to read and then infer the meaning of the words without making it look like a lesson.
At the same time, it provides engaging visual materials for those who learn better visually. It is an excellent book to learn where water comes from.
This book is more suitable for older kids (grades 3-5) because it talks more about the science of water and uses some advanced scientific terms.
Besides the remarkable paintings and pictures, this book also raises issues about the environment and really makes you think more about your daily usage of water.
It is a great complement to the water cycle experiment.
A Drop Around The World is one of teachers’ favorites.
It does a great job explaining what the water cycle is.
It doesn’t water-downed (no pun intended!) on facts and yet it uses language children can understand.
The best part — it is also very entertaining and interesting to kids of all ages.
If you are looking to buy one book on the topic “water cycle”, this is the one you should get!
A reader told me about this book and so I checked it out.
Through graceful, informative poetic verse, Water Dance tells a story of water dancing through different stages of the water cycle.
It is captivating and definitely not a boring fact-filled book.
The beautifully illustrated pictures are almost like a work of art. Kids will like reading it!
I’m so glad my reader alerted me to this great find. Keep the feedback coming!
It is a great book to discuss why we should always conserve water and perfect to read during a school unit on Water Cycle, Water Conservation or Saving the Earth.
Although this book makes the mistake of oversimplifying the reasons for saving water, it still provides a good starting point for kids to think about the importance of saving water. Suitable for elementary school units.