☰ خطة العام · العلوم (بالإنجليزية)

Tiny plastic, precious water, and where it is

الأسبوع 18 · المحور الثالث «حماية كوكبنا»، الوحدة الثالثة «الموارد الموجودة على سطح الأرض»، المفهوم 3.1 (ج) والمفهوم 3.2 «الماء كأهم الموارد الطبيعية على سطح الأرض» (أ): البلاستيك في الماء وتوزيع الماء · 3 دروس
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Where on Earth is the water?

Discovery Education Science P5: Term 2, Unit 3, pp. 36–40
GoalDescribe how Earth’s water is shared between salt water and fresh water, name the oceans, and show the shares in a pie graph.
New words
ocean · a very large body of salt water; there are five on Earthgroundwater · water stored in the cracks and spaces of rock undergrounddelta · a fan of land made by mud dropped where a river meets the sea
Explanation

More than two thirds of Earth’s surface is covered by water. About 97 out of every 100 parts of all the water are salty, and they are in the oceans and seas. The five oceans are the Arctic, Atlantic, Indian, Pacific and Southern oceans. The Mediterranean and the Red Sea are seas. Only about 3 out of every 100 parts are fresh water. Fresh water is found as ice in glaciers, underground, and in rivers, streams, lakes and ponds. Groundwater fills cracks and spaces in rock, and there is more of it than in all the rivers and lakes together. Egypt’s oases use it. A river often begins as a fast stream in the mountains. Near its end, it slows and drops the mud it carried, which builds a delta. The Nile Delta is one. To compare shares we can draw a pie graph, where each slice shows a part of the whole.

97%salt waterfresh water
Worked examples
about 97 salt, about 3 fresh
Picture 100 squares, one for each part of Earth’s water. About 97 are salty and only about 3 are fresh.
Water bodyType of waterExample
oceansaltAtlantic Ocean
seasaltRed Sea
riverfreshthe Nile
groundwaterfreshwells in Siwa
Different water bodies hold different kinds of water.
How a delta forms. A stream runs fast from the mountains and carries mud. The river slows near the sea and drops the mud, which piles up into a fan of new land.
Class activity

One-litre Earth (a grown-up helps). Fill a 1-litre bottle with water and a little blue colour to stand for all of Earth’s water. 1 litre is 1000 mL, so the fresh water is about 3 out of 100 parts, which is 30 mL. Pour 30 mL into a spoon-sized cup or two tablespoons. That small amount shows how little of Earth’s water is fresh. Do not drink it.

Practice
1
Name the five oceans.
2
Imagine 200 cups of Earth’s water. About 3 in every 100 cups hold fresh water. About how many of the 200 cups are fresh, and how many are salty?
3
Which of these hold fresh water? A: the Red Sea, B: a pond, C: the Nile, D: the Mediterranean Sea.
4
What is groundwater, and where in Egypt do people use it?