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	EARTH STRUCTURE LESSON   
	Directions: 
	Print the Earth Structure        reading 
	comprehension passage and questions (see 
	below).   
	Students should read the passage 
	silently, then answer the questions.  Teachers may also use the text as 
	part of a classroom lesson plan.   
	Lesson Excerpt      You might think the earth is just a giant  ball made of rock and soil.  On the  surface, that is true.  The crust is the outermost surface of the  earth.  It is made of soil with a thick  layer of rock underneath.  Most of the  rocks that make up the crust are made of the elements silicon and oxygen.  Smaller amounts of aluminum, iron, calcium,  and other elements make up the rest.  The  crust is thicker beneath the continents and thinner under the oceans.  The thickness of the crust varies from five  to ten kilometers thick under the oceans, to between twenty and seventy  kilometers thick beneath the continents.   Underneath the rocky crust, the earth is very different.
 Underneath the crust lies the earth's mantle.  This layer of the earth is about 2,900  kilometers thick.  High temperatures  (2800 – 3200 degrees Celsius) melt the rocks of the mantle, forming a substance  called magma.  This thick, gooey layer has  a texture like thick oatmeal.  When magma  reaches earth's surface, like when a volcano erupts, it is called lava.
 Continued... 
      
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Earth Structure   
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 Includes reading passage, questions, 
and answer sheet. |          
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