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How Polarized Sunglasses Tame a Shiny Lake

8th grade nonfiction passage about polarized light and glare: 259 words, six questions, an answer key and vocabulary.

8th grade nonfiction polarized light and glare 259 words

How Polarized Sunglasses Tame a Shiny Lake

Anyone who has squinted at the sun's glittering path on a lake knows how painful glare can be. Ordinary dark sunglasses help by dimming everything equally, but the glare is still there, only dimmer, and the whole scene looks gloomy. Polarized sunglasses do something cleverer. They remove much of the glare while leaving the rest of the scene bright and clear.

To understand them, think of light as a wave that shakes sideways as it travels. Light from the sun shakes in all directions at once, like a mixture of waves wiggling up and down, side to side, and every angle between. This is called unpolarized light.

When light bounces off a flat, shiny surface such as water or a wet road, something changes. The reflected light is mostly made of waves that shake in one direction, which is sideways along the surface. That sideways light is what we experience as glare.

A polarized lens contains tiny chains of molecules lined up in the same direction, a bit like the slats of a picket fence. Waves that shake along the slats are blocked, while the rest pass through. The lenses are turned so that the blocked direction is sideways, which stops much of the reflected glare. Light that bounces off leaves and rocks keeps its mixed directions and mostly passes through.

Polarized lenses have a small drawback, however. Many phone and computer screens give off polarized light, so a screen may look dim or dark when you tilt your head while wearing them, and some people find that annoying.

Questions

  1. How do ordinary dark sunglasses deal with glare? in the text

  2. In which direction does most reflected glare shake? in the text

  3. What is a polarized lens compared to in the passage? in the text

  4. Why do polarized lenses cut glare but leave other things bright? think about it

  5. Why might a phone screen look dark through polarized sunglasses? think about it

  6. What kind of surfaces make reflected light mostly shake in one direction? in the text

Words to know

glare
a harsh, bright light that hurts the eyes
polarized
made to vibrate in mainly one direction
reflected
bounced back off a surface
molecules
tiny groups of atoms that make up matter
drawback
a small problem with something that is otherwise good
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One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 228 words · Flesch-Kincaid grade 4.1

Have you ever squinted at the sun's glitter on a lake? Glare can hurt your eyes. Ordinary dark sunglasses dim everything the same amount. The glare is still there, just dimmer. Polarized sunglasses are cleverer. They remove much of the glare and leave the rest of the scene bright and clear.

To see how, think of light as a wave that shakes sideways as it travels. Sunlight shakes in all directions at once. Some waves wiggle up and down. Some wiggle side to side. Others wiggle at every angle in between. This is called unpolarized light.

Light that bounces off a flat, shiny surface, like water or a wet road, changes. The reflected light is mostly waves that shake in one direction. That direction is sideways along the surface. This sideways light is the glare we feel.

A polarized lens has tiny chains of molecules lined up in one direction, like the slats of a picket fence. Waves that shake along the slats are blocked. The others pass through. The lenses are turned so that the blocked direction is sideways. That stops much of the glare. Light bouncing off leaves and rocks has mixed directions, so most of it passes through.

Polarized lenses have a small drawback. Many phone and computer screens give off polarized light. A screen may look dim or dark if you tilt your head.

▲ This passage · 259 words · Flesch-Kincaid grade 7.4

Anyone who has squinted at the sun's glittering path on a lake knows how painful glare can be. Ordinary dark sunglasses help by dimming everything equally, but the glare is still there, only dimmer, and the whole scene looks gloomy. Polarized sunglasses do something cleverer. They remove much of the glare while leaving the rest of the scene bright and clear.

To understand them, think of light as a wave that shakes sideways as it travels. Light from the sun shakes in all directions at once, like a mixture of waves wiggling up and down, side to side, and every angle between. This is called unpolarized light.

When light bounces off a flat, shiny surface such as water or a wet road, something changes. The reflected light is mostly made of waves that shake in one direction, which is sideways along the surface. That sideways light is what we experience as glare.

A polarized lens contains tiny chains of molecules lined up in the same direction, a bit like the slats of a picket fence. Waves that shake along the slats are blocked, while the rest pass through. The lenses are turned so that the blocked direction is sideways, which stops much of the reflected glare. Light that bounces off leaves and rocks keeps its mixed directions and mostly passes through.

Polarized lenses have a small drawback, however. Many phone and computer screens give off polarized light, so a screen may look dim or dark when you tilt your head while wearing them, and some people find that annoying.

■ Harder · 263 words · Flesch-Kincaid grade 9.6

Anyone who has squinted at the sun's glittering path across a lake understands how punishing glare can be. Ordinary dark sunglasses help by dimming everything equally, but the glare itself remains, merely subdued. Polarized sunglasses accomplish something considerably more sophisticated, because they remove much of the glare while leaving the remainder of the scene bright and clear.

To understand how they work, it helps to picture light as a wave that shakes sideways as it travels. Light from the sun vibrates in every direction at once, like a mixture of waves wiggling up and down, from side to side, and at every angle in between. Light of this kind is described as unpolarized.

When light bounces off a flat, shiny surface such as a lake or a wet road, something important changes. The reflected light consists mostly of waves that vibrate in a single direction, which is sideways along the surface. That sideways light is precisely what we experience as glare.

A polarized lens contains tiny chains of molecules aligned in the same direction, rather like the slats of a picket fence. Waves that vibrate along the slats are absorbed, while the others pass through. Manufacturers turn the lenses so that the blocked direction is sideways, which eliminates much of the reflected glare. Light bouncing off leaves and rocks keeps its mixture of directions, so most of it still passes through.

Polarized lenses do have a minor drawback. Many phone and computer screens emit polarized light, so a screen can appear dim or even dark when you tilt your head while wearing them.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put glare, polarized, reflected, molecules and drawback on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 3 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 4 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "How Polarized Sunglasses Tame a Shiny Lake"?

It was written for 8th grade. It has 259 words and works out to a Flesch-Kincaid grade level of about 7.4. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 4 ask for something the text says directly and 2 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 3 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

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