# HOW MUCH OF EARTH’S WATER CAN WE USE? – B

Last updated: July 7, 2020

Math Skill: Percentages, decimals & fractions

Science Skill: Earth Water

Environmental Area: Water

Area level: Global-scale

Purpose: Understand scarcity of our freshwater resources and develop awareness of water quality

### BACKGROUND FOR THE TEACHER

You may think there is a lot of water available for us to use on Earth because more than 70 percent of the Earth’s surface is covered by water.  However,almost all of the Earth’s water is classified as saltwater in the oceans that cannot be consumed by humans.  Freshwater accounts for only 2.5% of the Earth’s water.

As the Ohio River is the major source of fresh water in Southwest Indiana, river water is a very valuable water resource to us. Rivers are particularly precious because the total volume of rivers equals only one millionth of the total volume of Earth’s water.

### TEACHER GUIDE

The purpose of this activity is to practice solving percent problems while giving your students an idea of thepreciousness of the water that we daily consume.  This activity was created based on data obtained from U.S. Geological Survey.

Math Skill: Percentages, decimals & fractions

Using the percentage of saltwater and freshwater on Earth, rounded to 97% and 3%, respectively, students are asked tocolor the portion of salt water green and the portion of freshwater blue on a grid of 100 boxes. Students are then asked to convert them to decimals and fractions.

### SIMILAR PROBLEM

Math Skill: Percentages, decimals & fractions

Using the colored grid of 100 boxes which shows the distribution of surface water on Earth, students are asked to find out the percentages of lakes, rivers, and swamps.  Students are then asked to convert them to decimal and fraction.