Last updated: July 7, 2020

Math Skill: Converting from percentages to decimals & fractions (Percentages, decimals & fractions )

Science Skill: Earth Water

Grade level: 4th & 5th grades

Environmental Area: Water

Area level: Global-scale

Purpose: Learn distribution of river water in the world and raise awareness of water conservation



Most of the freshwater is stored in glaciers/icecaps or underground in the world. The remainder—surface water (lakes, swamps, rivers, and snow on the top of the mountains)—consists of only 1.3% of the total freshwater.

Our fresh water resources arenot equally distributed on Earth. For example, as much as 50% of the world’s lake water is located in Canada alone. The world’s largest fresh water basin is in the Amazon. Together with the Orinoco basin in South America, the Amazon basin consists of 15% of world’s runoff.  On the other hand, only 0.3% of the river water is found in Middle East and North Africa combined.

The circle graph shows distribution of water resources by region. It shows that the fourth largest volume of water resources is located in North America after South America, Asia, and Europe.

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Source:Food and Agriculture Organization of the United Nations (FAO)



Ohio River and disrupted water cycle


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The purpose of this activity is to improve students’ skills in data analysis and number operations through interpreting the circle graph while giving them an idea how the river water is (unequally) distributed on earth.


worksheet & answer key

Math Skill: Converting from percentages to decimals & fractions (Percentages, decimals & fractions )

Using a circle graph that shows distribution of river water on earth in percentages, students are asked to convert from percentages to decimals and fractions.



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