How Much Freshwater Does Earth Have?

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SWBAT make a model to understand the quantity of freshwater on Earth. SWBAT create, apply, and analyze a pie chart to communicate that freshwater is scarce.

Big Idea

Water, water, everywhere....make a model and investigate to find out how much freshwater is available on Earth and how to use this resource wisely.


5 minutes


At this point in the year, students are familiar with the procedures for an inquiry, so I chunk the lesson to let them work more independently. I ask students to read the question and background information on the worksheet. Doing this will engage students in the lesson and learning. I want students to work collaboratively with their peer group on this part of the inquiry, so I provide about 5 minutes and then check back with the class. 

I circulate the classroom while students are working to assess their understanding, clarify any misconceptions, and answer questions. Then I can determine when students are ready to share and move to the next step. 

Earth's Resources Unit: This is a short, interactive unit that students can be engaged in at the end of the school year. It helps keep students focused on science while learning important information about Earth's resources. As student's progress through the unit, they will work towards MS-ESS3-4 constructing an argument supported by evidence for how increases in human population and per capita consumption of natural resources impacts Earth's systems.

Unit Description: What are the advantages of using Earth's resources wisely? Where do we get energy? Students evaluate the biodegradability of renewable and nonrenewable natural resources while using critical thinking skills to create an energy exhibit focusing on energy sources.

Explore: A Freshwater Model

20 minutes


I chunk the next part of the inquiry so that students can investigate, collect data, and analyze information with their peers. Through this inquiry, I want students to be able to MS-ESS3-4 construct an argument supported by evidence from how increases in human population and per-capita consumption of natural resources impact Earth's systems. The lesson allows me to assess if students understand how much freshwater Earth has and the advantages of using Earth's resources wisely.

As students investigate, there are a variety of standards woven throughout the learning. Students (SP#1) ask questions during the inquiry and (SP#2) develop and use a model (containers showing amounts of water on Earth) to explain "Where is Earth's water?" Students (SP#3) carry out an investigation, (SP#4) analyze and interpret data collected to come to a conclusion about the amount of freshwater on Earth. Students (SP#5) use mathematics and computational thinking to identify relationships from the model, then (SP#7) collaborate with their peers to search for the best explanation to their findings from the inquiry. Ultimately, students will (SP#8) accurately communicate their findings in a pie chart in order to engage in discourse with their peers. Math Practices are tied into the lesson as well. (MP#5) students use appropriate tools (graduated cylinder, beaker, protractor, compass) strategically and (MP#6) attend to precision as they accurately measure in each part of the inquiry.

Throughout the lesson, students use science process skills. These skills teach students to think and provide a foundation for learning more complex skills. In the inquiry, students develop skills such as observing, measuring, communicating, and predicting. When students predict about the amount of freshwater and the impacts of using this resource wisely, they are stating the outcome of a future event based on a pattern of evidence show in their pie chart.

Explain: Graph The Data

15 minutes


This part of the lesson helps students explain the concepts (resources, freshwater) they have been exploring. They have opportunities to verbalize their conceptual understanding with their peers and demonstrate new skills as they create a pie chart from data collected. I ask students to collaborate with their partner, discuss the freshwater model and investigation, and come to a conclusion about the amount of freshwater on Earth.

Next, I guide students in creating a pie chart with the data and then ask them to explain how the pie chart helps communicate that freshwater is scare. Before making the pie chart, I show the video so that students can visually understand the process. After the video, I work with small groups of students to create their pie chart. As I circulate the classroom, I formatively assess student learning of this mathematical process.

Using a protractor to make a pie chart

Finally, students reflect and write a conclusion. This step is very important for students to "come full circle."

I have learned that you need to take students back to the question so they can think about the process. How much freshwater does Earth have? Take 2 minutes for students to process this question and write a conclusion. I give them a sentence starter to help with the process, for example:  I learned that . . .because. . .  Take 2 minutes to share answers with the class so students can hear other student thoughts.

Some students wrote:

  • I learned that Earth's freshwater is scarce because there is 97% saltwater and about 3% fresh, according to the pie chart.
  • I learned that ground and freshwater are low because we just don't have a lot of it.
  • I learned that we should try and save freshwater because the majority of Earth is ocean water (salt) and not fresh.