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1、Color BlindnessA Reading AZ Level Q Leveled BookWord Count:826Visit www.readinga- for thousands of books and materials.Writing Choose two forms of color blindness.Write a report that compares the two conditions and their effects on a persons life.MathResearch the statistics about the number of peopl
2、e with the various forms of color blindness in your country.Organize your results in a pie chart.Connectionswww.readinga-Color BlindnessQTWWritten by Cheryl ReifsnyderLEVELED BOOK Qwww.readinga-What causes color blindness,and how can it affect a persons life?Focus QuestionWritten by Cheryl Reifsnyde
3、rColor BlindnessCorrelationLEVEL QN3030Fountas&PinnellReading RecoveryDRAColor BlindnessLevel Q Leveled Book Learning AZWritten by Cheryl ReifsnyderAll rights reserved.www.readinga-Photo Credits:Front cover,back cover:pretoperola/123RF;title page(both):shironosov/iStock/Thinkstock;page 3:Vronique Bu
4、rger/Science Source;page 4(both):Michael Shake/D;page 5:Designua/D;page 6(top):Gunilla Elam/Science Source;page 6(bottom):Steve Gschmeissner/Science Source;page 7(both):Ted Kinsman/Science Source;page 8(left,both):anatchant/iStock/Thinkstock;page 8(center,both):Nadezhda Bolotina/Hemera/Thinkstock;pa
5、ge 8(right,both):iremphotography/iStock/Thinkstock;page 9(all):Popartic/iStock Editorial/Thinkstock;page 10(both):Dorling Kindersley/Thinkstock;page 11:RVN/Alamy Stock Photo;page 12:Alexander Kaludov/123RF;page 13:EnChroma;page 14:Neitz Laboratory;page 15:Phanie/Alamy Stock Photoappscolor-blindcone
6、cellsgeneretinarod cellssensitivetissuewavelengthWords to Know3Table of ContentsWhat Colors Do You See?.4Where Do Colors Come From?.5How Color Vision Works .6Rods and Cones .7Different Types of Color Blindness .8Color Blindness Is No Joke .11Testing for Color Blindness .12Tools to Help Color-Blind P
7、eople .13Treating Color Blindness .14Color Vision for All?.15Glossary .16Color Blindness Level Q4What Colors Do You See?Imagine looking at a box of crayons and seeing only shades of gray,blue,and yellow.Thats what they look like to many people who are color-blind.Most people who are color-blind can
8、still see some colors.They just cant see as many colors as other people.Choosing a red crayon is much easier for someone with full-color vision(top)than someone with red-green color blindness(bottom).3Table of ContentsWhat Colors Do You See?.4Where Do Colors Come From?.5How Color Vision Works .6Rods
9、 and Cones .7Different Types of Color Blindness .8Color Blindness Is No Joke .11Testing for Color Blindness .12Tools to Help Color-Blind People .13Treating Color Blindness .14Color Vision for All?.15Glossary .16Color Blindness Level Q4What Colors Do You See?Imagine looking at a box of crayons and se
10、eing only shades of gray,blue,and yellow.Thats what they look like to many people who are color-blind.Most people who are color-blind can still see some colors.They just cant see as many colors as other people.Choosing a red crayon is much easier for someone with full-color vision(top)than someone w
11、ith red-green color blindness(bottom).5Where Do Colors Come From?White light has every color of the rainbow hidden inside it.Each color is a different wavelength.Things appear to be different colors because they absorb and reflect different wavelengths of light.A strawberry looks red because it refl
12、ects red wavelengths while absorbing most others.Color Blindness Level Q6How Color Vision WorksPeople see colors because our eyes respond differently to different wavelengths of light.When light enters one of your eyes,it gets focused on the retina.The retina is a thin layer of tissue at the back of
13、 the eyeball.The light triggers rod cells and cone cells.These cells send signals to the brain,which uses the signals to make images.rodsThe cornea gathers and begins to focus light from the outside world.The iris opens or closes the pupil to allow more or less light into the eye.The lens changes sh
14、ape to finish focusing.The pupil is a hole in the center of the eye that allows light to pass through.conesHow an Eye SeesRods and cones lining the wall of the retina at the back of the eye register what is being seen.The optic nerve sends messages to the brain about what the eye is seeing.5Where Do
15、 Colors Come From?White light has every color of the rainbow hidden inside it.Each color is a different wavelength.Things appear to be different colors because they absorb and reflect different wavelengths of light.A strawberry looks red because it reflects red wavelengths while absorbing most other
16、s.Color Blindness Level Q6How Color Vision WorksPeople see colors because our eyes respond differently to different wavelengths of light.When light enters one of your eyes,it gets focused on the retina.The retina is a thin layer of tissue at the back of the eyeball.The light triggers rod cells and c
17、one cells.These cells send signals to the brain,which uses the signals to make images.rodsThe cornea gathers and begins to focus light from the outside world.The iris opens or closes the pupil to allow more or less light into the eye.The lens changes shape to finish focusing.The pupil is a hole in t
18、he center of the eye that allows light to pass through.conesHow an Eye SeesRods and cones lining the wall of the retina at the back of the eye register what is being seen.The optic nerve sends messages to the brain about what the eye is seeing.7Rods and ConesRod cells are the most sensitive cells in
19、 your retina.They let you see in very low light.However,they cant tell different colors apart.Cone cells handle color vision.There are three types of cone cells.One type absorbs blue light,one green light,and one red light.Combining these three main colors allows us to see thousands of colors.When o
20、ne or more types of cone cells arent working,though,color blindness results.Color Vision in AnimalsMost animals can see fewer colors than humans.For instance,dogs can only see shades of blue and yellow,and bulls are completely color-blind!Other animalsincluding some birds,bees,and butterfliessee mor
21、e colors than humans do,including wavelengths of light that are invisible to humans.human visionhoneybee visionColor Blindness Level Q8Different Types of Color BlindnessRed-Green Color BlindnessPeople with red-green color blindness have trouble telling red and green apart.This is the most common typ
22、e of color vision problem.It affects about one out of every twelve men and one out of every two hundred women.People with red-green color blindness usually have something wrong with their green cone cells.As a result,green and yellow objects appear reddish in color.Sometimes red-green color blindnes
23、s is caused by a missing or damaged red cone cell.In this case,red,orange,and yellow objects appear green or black.full-color visionred-green color-blind visionredredyellowyellowgreengreen7Rods and ConesRod cells are the most sensitive cells in your retina.They let you see in very low light.However,
24、they cant tell different colors apart.Cone cells handle color vision.There are three types of cone cells.One type absorbs blue light,one green light,and one red light.Combining these three main colors allows us to see thousands of colors.When one or more types of cone cells arent working,though,colo
25、r blindness results.Color Vision in AnimalsMost animals can see fewer colors than humans.For instance,dogs can only see shades of blue and yellow,and bulls are completely color-blind!Other animalsincluding some birds,bees,and butterfliessee more colors than humans do,including wavelengths of light t
26、hat are invisible to humans.human visionhoneybee visionColor Blindness Level Q8Different Types of Color BlindnessRed-Green Color BlindnessPeople with red-green color blindness have trouble telling red and green apart.This is the most common type of color vision problem.It affects about one out of ev
27、ery twelve men and one out of every two hundred women.People with red-green color blindness usually have something wrong with their green cone cells.As a result,green and yellow objects appear reddish in color.Sometimes red-green color blindness is caused by a missing or damaged red cone cell.In thi
28、s case,red,orange,and yellow objects appear green or black.full-color visionred-green color-blind visionredredyellowyellowgreengreen9Blue-Yellow Color BlindnessBlue-yellow color blindness happens when blue cone cells are missing or not working properly.This type of color blindness is fairly rare.Its
29、 only found in about one out of every ten thousand people worldwide.Unlike red-green color blindness,its equally common in men and women.Color Blindness Level Qfull-color visionred-green color blindnessblue-yellow color blindness 10Complete Color BlindnessComplete color blindness is the most serious
30、 type of color blindness.It happens when a person has problems with two or three types of cone cells.People who are missing several types of cone cells tend to be very sensitive to light.They may also have difficulty seeing clearly,especially in bright light.This is because they rely on rod cells fo
31、r most or all of their vision.Rod cells only work in low light.About one in thirty thousand people worldwide are missing all three types of cone cells.People without any working cone cells only see shades of black,white,and gray.Complete color blindness(right)is very rare.9Blue-Yellow Color Blindnes
32、sBlue-yellow color blindness happens when blue cone cells are missing or not working properly.This type of color blindness is fairly rare.Its only found in about one out of every ten thousand people worldwide.Unlike red-green color blindness,its equally common in men and women.Color Blindness Level
33、Qfull-color visionred-green color blindnessblue-yellow color blindness 10Complete Color BlindnessComplete color blindness is the most serious type of color blindness.It happens when a person has problems with two or three types of cone cells.People who are missing several types of cone cells tend to
34、 be very sensitive to light.They may also have difficulty seeing clearly,especially in bright light.This is because they rely on rod cells for most or all of their vision.Rod cells only work in low light.About one in thirty thousand people worldwide are missing all three types of cone cells.People w
35、ithout any working cone cells only see shades of black,white,and gray.Complete color blindness(right)is very rare.11Color Blindness Is No JokeColor blindness can cause serious problems.People who are color-blind have trouble reading maps.Color-blind children may have trouble in school.Color blindnes
36、s can also cause safety issues.Fire hydrants and emergency equipment are often colored red or yellow to make them more visible.Someone who is color-blind may not notice bright colors that stand out to those with full-color vision.Color blindness can even limit a persons career choices.Some jobs,such
37、 as airline pilot,require full-color vision.Others,such as photographer,are much more difficult without full-color vision.Color Blindness Level QSome traffic lights use shapes as well as colors to convey information to color-blind drivers.12Testing for Color BlindnessDoctors use several types of tes
38、ts to find out if a person has color blindness.One test uses images made up of dots that are different sizes and colors.People with full-color vision can see numbers or shapes inside the pictures.People with red-green color blindness have trouble spotting the hidden symbols.Can you see the hidden nu
39、mbers or shapes in the circles in this color vision test?11Color Blindness Is No JokeColor blindness can cause serious problems.People who are color-blind have trouble reading maps.Color-blind children may have trouble in school.Color blindness can also cause safety issues.Fire hydrants and emergenc
40、y equipment are often colored red or yellow to make them more visible.Someone who is color-blind may not notice bright colors that stand out to those with full-color vision.Color blindness can even limit a persons career choices.Some jobs,such as airline pilot,require full-color vision.Others,such a
41、s photographer,are much more difficult without full-color vision.Color Blindness Level QSome traffic lights use shapes as well as colors to convey information to color-blind drivers.12Testing for Color BlindnessDoctors use several types of tests to find out if a person has color blindness.One test u
42、ses images made up of dots that are different sizes and colors.People with full-color vision can see numbers or shapes inside the pictures.People with red-green color blindness have trouble spotting the hidden symbols.Can you see the hidden numbers or shapes in the circles in this color vision test?
43、13Tools to Help Color-Blind PeopleSo far,doctors cant cure color blindness.However,many new tools can help people deal with color blindness.Smartphone apps can do tasks such as identifying colors and picking colors that go together well.These apps can help people choose matching clothes or tell whic
44、h fruits are ripe at the grocery store.Researchers have also created high-tech sunglasses that filter out specific wavelengths of light.The sunglasses make it possible for people with red-green color blindness to tell the two colors apart.These special glasses from EnChroma allow people with red-gre
45、en color blindness to see a much more colorful world.Color Blindness Level Q14Treating Color BlindnessScientists recently corrected red-green color blindness in squirrel monkeys.The monkeys lacked red cone cells.As a result,they couldnt tell the difference between red and green.Researchers were able
46、 to insert the missing gene into cells in the monkeys eyes.Within about twenty weeks,the monkeys could tell the difference between red and green dots.These successful experiments in squirrel monkeys provide hope for a cure in humans.A squirrel monkey takes a color vision test as part of an experimen
47、t.13Tools to Help Color-Blind PeopleSo far,doctors cant cure color blindness.However,many new tools can help people deal with color blindness.Smartphone apps can do tasks such as identifying colors and picking colors that go together well.These apps can help people choose matching clothes or tell wh
48、ich fruits are ripe at the grocery store.Researchers have also created high-tech sunglasses that filter out specific wavelengths of light.The sunglasses make it possible for people with red-green color blindness to tell the two colors apart.These special glasses from EnChroma allow people with red-g
49、reen color blindness to see a much more colorful world.Color Blindness Level Q14Treating Color BlindnessScientists recently corrected red-green color blindness in squirrel monkeys.The monkeys lacked red cone cells.As a result,they couldnt tell the difference between red and green.Researchers were ab
50、le to insert the missing gene into cells in the monkeys eyes.Within about twenty weeks,the monkeys could tell the difference between red and green dots.These successful experiments in squirrel monkeys provide hope for a cure in humans.A squirrel monkey takes a color vision test as part of an experim