☰ خطة العام · العلوم (بالإنجليزية)

Term 2 review: Earth’s resources and patterns in the sky

الأسبوع 30 · مراجعة الفصل الدراسي الثاني: الموارد الموجودة على سطح الأرض والأنماط في السماء · 3 دروس
1

Review: water and Earth’s spheres

Discovery Education Science P5: Term 2, Units 3–4
GoalReview the four spheres, where Earth’s water is found, watersheds, microplastics and clues to clean water, using new questions.
New words
hydrosphere · all the water on Earth, in oceans, rivers, ice, underground and in the airbiosphere · all living things on Earthwatershed · all the land whose water flows to the same stream, river or lake
Explanation

Earth has four connected systems: the geosphere (land and rock), the atmosphere (air), the hydrosphere (all water) and the biosphere (all life). They interact all the time: rain from the air fills a river, a palm drinks from the ground, a fish breathes the oxygen in the water. More than two thirds of Earth is covered by water, but about 97 out of every 100 parts of it are salty. Of the small fresh part, most is frozen in glaciers and ice or lies underground, so only a very little is easy to reach in rivers and lakes. The Nile gives Egypt almost all its water, and oases such as Siwa use groundwater. A watershed is all the land that drains to one place, so pollution upstream reaches those downstream. Microplastics are plastic pieces smaller than 5 mm, which small animals can mistake for food. Some water insects live only in clean water, so finding them is a clue that a stream is healthy.

geosphereatmospherehydrospherebiosphere
Worked examples
2004006008001000mL
Imagine a 1000 mL jug standing for all the water on Earth. About 97 of every 100 parts are salty, so 970 mL stands for salt water and 1000 − 970 = 30 mL for fresh water. Most of that 30 mL would be ice or underground.
What happensSpheres
a camel drinksbiosphere, hydrosphere
rain wears a rockatmosphere, hydrosphere, geosphere
Which spheres interact? A camel drinks at an oasis: the biosphere (camel) and the hydrosphere (groundwater). Rain wears a rock: the atmosphere (weather), the hydrosphere (rain) and the geosphere (rock).
024681093clean-water insectspoor-water insectsinsects
A class counts insects in a creek. They find 9 that need clean water and 3 that live in poor water. That is 9 + 3 = 12 insects, and 9 − 3 = 6 more clean-water insects. This is a clue that the creek is quite healthy, though not proof. Pieces of plastic of 2 mm are microplastics. A piece of 8 mm is not.
Class activity

Review poster. On one page draw four boxes for the four spheres. In each write two examples from your own neighbourhood. Draw arrows between boxes to show two interactions, for example “rain falls on fields”. Add a small bar to show how little of Earth’s water is fresh. Share your poster with a friend and ask which interaction they would add.

Practice
1
Name the four spheres and give one example of each.
2
In a 500 mL jug standing for all Earth’s water, about 97 of every 100 parts are salty. How many mL stand for fresh water?
100200300400500mL
3
A farm upstream washes chemicals into a stream. Which place gets them last: a village, a town or the sea?
4
Why is finding clean-water insects only a clue and not proof that water is safe to drink?