MEASUREMENT 2


Latin Roots


TAKING INVENTORY: PRETEST Assess students’ prior knowledge of Part 2 vocabulary words by using the Part 2 Pretest on page T241. Answers: 1.J 2.B 3.C 4.E 5.H 6.A 7.G 8.I 9.D 10.F.


OBJECTIVES Students will C read and discuss an essay related to this unit’s theme— Measurement.


C activate their prior knowledge about the theme to learn the meanings of ten words.


GUIDE STUDENTS Activating Prior Knowledge Discuss the following questions before students read “Measuring Our Atmosphere: The Ozone Layer.” C What do you know about the ozone layer?


C What do you think can hurt the ozone layer? Why?


Have students share any prior knowl- edge they have about the essay’s ten boldfaced words. Have them take turns reading the essay aloud or silently, depending on the needs and abilities of your students. Compare and contrast students’ prior knowl- edge and their new understanding of these ten words.


MEASUREMENT 2 Latin Roots


The Ozone Layer Measuring Our Atmosphere:


Is our planet in danger? We hear a lot of talk about the environment. We know that there is a hole in the ozone layer. But what exactly is the ozone layer?


Y


ou probably know that Earth’s atmosphere separates our planet from space, but did you know that there are several layers that make up the atmosphere? From the closest to Earth toward space, they are the troposphere, the stratosphere, the mesosphere, and the thermosphere. These layers of air are full of minuscule molecules of elements. The elements that make up our atmos- phere do not have equality—some ele- ments are much more abundant than others. For instance, there is plenty of nitrogen—it makes up 80 percent of the atmosphere. Nearly 20 percent is made of oxygen. What’s left is a group of other molecules, including water, argon, car- bon dioxide, and ozone. Ozone makes up about 0.01 percent of the atmosphere. This amount might seem diminutive, especially compared to the large amount of nitrogen, but the ozone layer’s job is very important.


Ozone molecules are found in the stratosphere. It is the ozone layer that protects Earth from the sun’s harmful rays. Think of ozone molecules as a natural sunscreen. Without adequate protection from the sun, everything gets too many harmful rays and burns. In fact, these unhealthy sun rays are believed to cause


skin cancer, cataracts, and other problems. In the early 1980s, scientists discovered that these important ozone molecules were being depleted. Some scientists thought that natural substances, such as those from volcanoes and from the ocean, might play a minor role in the destruction of ozone molecules. After further study, they learned that this re- duction was actually caused by some substances used by humans. These damag- ing substances are called chlorofluoro- carbons, or CFCs. Some aerosol cans are replete with these chemicals. Since these discoveries, scientists, world leaders, and everyday people have taken steps to protect the ozone layer. The ozone layer has the ability to repair itself. Over time, molecules that make up the ozone layer are created and destroyed. Nature has always kept an equable relationship between the ozone molecules created and those destroyed. But human overuse of chemicals has changed this balance. Now that humans are aware of this problem, perhaps we will be more careful with the chemicals we use. Then nature can try to take over again. But the shift in balance won’t occur overnight. Scientists think that it will take at least fifty years for the ozone to restore its equilibrium. We humans have to help the ozone achieve this balance. When you hear the words Save the Earth, remember that the ozone is a part of our Earth. This planet and the atmosphere around it hold your future!


for Wisdom Word


122 Measurement Part 2


Part 2 Daily Planner Day 1


Pretest, p. T241


Unlock Through Context Reading Selection, p. 122


Practice the Context Clues Strategy, p. 123


Day 2 Day 3 Day 4


Day 5


Home Connection, p. T212 Unlock the Meanings, p. 124


Unlock the Meanings, p. 125 Process the Meanings, p. 126


Apply What You’ve Learned, p. 127


Speak It!, p. 127 Posttest, p. T241


T122 Unit 6 Measurement Part 2


Page(s) to Use


Strategy/Skills Assess prior knowledge.


Read words in context. Practice the strategy.


Learn the Latin roots equ, min, ple.


Use roots and the pre- fixes ad-, de-.


Identify synonyms and antonyms.


Choose the correct word.


Demonstrate word knowledge.


Apply skills to speaking.


Assess students’ knowledge.


WORD LIST minuscule equality plenty


diminutive adequate deplete minor replete equable


equilibrium


T


T


P


P


R


R A


A


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