GO IN DEPTH

Models of the Water Cycle

Introduction

Water cycling in and out of earth’s atmosphere and into the oceans and land is a very important process. This process, called the water cycle, is essential to life on earth. In this activity, you will build two different models of the water cycle process and then you will decide which of the models is most useful in helping you to understand the process.

Exploration

Begin by visiting The Water Cycle. As you are watching the animation, answer the following questions in your science journal. You will discuss them with your class:

• When and why does it rain?
• What happens to the rain water once it reaches the ground?
• What happens to the water when the sun comes out?
• What happens to the vapor in the air when it gets cold?

Check with your teacher before continuing. Next, view the illustration of the water cycle on Thirstin’s Water Cycle Adventure site. Based on what you know about the water cycle, be prepared to discuss these questions:

• Does the illustration do a good job of showing the water cycle?
• Can you think of ways that it can be improved?

Now you will work with a group to build two models of the water cycle, using materials that your teacher has provided.

Model 1
Instructions for the first model can be found at Building Models of the Water Cycle. To build this model, your group will need two half gallon jars, a rock, masking tape, and food coloring. After you have built the model, watch and see what happens to it as it warms on a sunny windowsill. Record what you observe in your science journal or notebook. In your own words, describe how the model explains what happens in the water cycle.

Model 2
Instructions for the second model can be found at Going Further: Build a Model of the Water Cycle. To build this model, your group will need a large Ziploc® plastic baggie, food coloring, masking tape, and a thermometer with a large range. In addition to building the model, you should reflect upon and explain what the model shows. In your own words, describe how the model explains what happens in the water cycle.

After your group has built both of the models, be prepared to discuss these questions with the class:

• How accurately do the models represent the process of the water cycle?
• How are the models alike? How are they different?
• Was one more simple than the other?
• Which one does a better job of explaining the water cycle? Why?
• Which did you find most useful in helping you understand the water cycle?
• Is there an aspect of the water cycle that is not well represented by either model? If so, how could you change the model to make it better?

This esheet is a part of the Models of the Water Cycle lesson.