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Swirling Colors on a Soap Bubble

5th grade nonfiction passage about thin films and light: 210 words, six questions, an answer key and vocabulary.

5th grade nonfiction thin films and light 210 words

Swirling Colors on a Soap Bubble

A soap bubble drifts through a sunny window, and its surface glitters with swirling pinks, greens, and blues. Yet the soap and water in the bubble have no color at all. Where do the colors come from?

The answer starts with the wall of the bubble. It is a thin skin of soapy water, far thinner than a sheet of paper. Sunlight looks white, but it is really a mix of every color of light, and light travels in waves. When sunlight reaches the bubble, some of it bounces off the outer face of the skin. Some goes into the skin and bounces off the inner face. The two bounced beams then meet.

Depending on how thick the skin is, the waves of one color may line up and grow stronger, while the waves of another color may cancel each other out. So one spot may show bright green while another spot shows bright blue. Because the skin is not the same thickness everywhere, you see a patchwork of colors.

The skin keeps changing, too. Gravity slowly pulls the water downward, so the top of the bubble grows thinner. The colors shift and swirl as this happens. Just before the bubble pops, its thinnest part may look clear or dark.

Questions

  1. What colors glitter on the bubble's surface? in the text

  2. Does the soapy water have any color of its own? in the text

  3. What is the wall of a bubble like? in the text

  4. What is sunlight really made of? in the text

  5. Why do you see a patchwork of colors? think about it

  6. Why do the colors shift and swirl as time passes? think about it

Words to know

glitter
to sparkle with many bright flashes
wave
a pattern that light and sound move in
beam
a narrow stream of light
cancel
to wipe out the effect of something
gravity
the pull that draws things toward the ground
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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 · 198 words · Flesch-Kincaid grade 2.6

A soap bubble floats past a sunny window. Its skin shines with swirls of pink, green and blue. But the soap and water have no color at all. So where do the colors come from?

It starts with the wall of the bubble. It is a thin skin of soapy water. It is much thinner than a sheet of paper. Sunlight looks white, but it is really a mix of every color of light. Light moves in waves. When sunlight hits the bubble, some of it bounces off the outside of the skin. Some goes into the skin and bounces off the inside. The two beams then meet.

The thickness of the skin matters. For one color, the waves line up and get stronger. For another color, the waves cancel each other out. So one spot may look bright green and another may look bright blue. The skin is not the same thickness everywhere. That is why you see a patchwork of colors.

The skin keeps changing. Gravity slowly pulls the water down. The top of the bubble gets thinner. The colors shift and swirl. Just before the bubble pops, the thinnest part may look clear or dark.

▲ This passage · 210 words · Flesch-Kincaid grade 4.9

A soap bubble drifts through a sunny window, and its surface glitters with swirling pinks, greens, and blues. Yet the soap and water in the bubble have no color at all. Where do the colors come from?

The answer starts with the wall of the bubble. It is a thin skin of soapy water, far thinner than a sheet of paper. Sunlight looks white, but it is really a mix of every color of light, and light travels in waves. When sunlight reaches the bubble, some of it bounces off the outer face of the skin. Some goes into the skin and bounces off the inner face. The two bounced beams then meet.

Depending on how thick the skin is, the waves of one color may line up and grow stronger, while the waves of another color may cancel each other out. So one spot may show bright green while another spot shows bright blue. Because the skin is not the same thickness everywhere, you see a patchwork of colors.

The skin keeps changing, too. Gravity slowly pulls the water downward, so the top of the bubble grows thinner. The colors shift and swirl as this happens. Just before the bubble pops, its thinnest part may look clear or dark.

■ Harder · 236 words · Flesch-Kincaid grade 7.9

A soap bubble drifts lazily through a sunlit window, and its delicate surface shimmers with swirling bands of pink, green, and blue. Strangely, the soap and water that form the bubble have no color whatsoever. So where do all of those brilliant colors originate?

The answer begins with the wall of the bubble, which is an extremely thin skin of soapy water, far thinner than a single sheet of paper. Sunlight appears white, but it is actually a blend of every color of light, and light travels in waves. When sunlight reaches the bubble, part of it reflects off the outer face of the skin, while part of it enters the skin and reflects off the inner face. The two reflected beams then meet one another.

Depending on how thick the skin happens to be at that spot, the waves of one color may line up and grow stronger, while the waves of another color may cancel each other out. Consequently, one region may glow bright green while a neighboring region glows bright blue. Because the skin varies in thickness from place to place, you observe a patchwork of colors.

The skin never stops changing, either. Gravity slowly drags the water downward, which causes the top of the bubble to grow thinner and thinner. The colors shift and swirl as this happens. Shortly before the bubble finally bursts, its thinnest part may appear clear or dark.

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 glitter, wave, beam, cancel and gravity 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 2 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 5 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 "Swirling Colors on a Soap Bubble"?

It was written for 5th grade. It has 210 words and works out to a Flesch-Kincaid grade level of about 4.9. 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 2 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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