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Why a Humming Fork Gets Louder on a Table

6th grade nonfiction passage about vibration and loudness: 226 words, six questions, an answer key and vocabulary.

6th grade nonfiction vibration and loudness 226 words

Why a Humming Fork Gets Louder on a Table

Strike a tuning fork on your knee and hold it in the air. You will hear a faint, pure note. Now touch the end of its handle to a tabletop. Suddenly the sound gets much louder, as if someone had turned up a volume knob. Nothing was added to the fork, so what changed?

Every sound begins with something vibrating. The two thin prongs of the fork swing back and forth many times each second. But prongs are narrow, so they push very little air with each swing, and your ear receives only a weak signal.

A tabletop is large and flat. When the fork's handle touches it, the vibrations travel into the wood and make the whole surface shake a little. Because a big surface pushes on much more air than a thin prong does, it sends out a stronger sound wave. The table is working like a loudspeaker for the fork.

Musical instruments use the same idea. The strings of a guitar make only a quiet sound alone. They pass their vibrations to the hollow wooden body, which shakes along with them and fills the room. There is a catch, however. The fork has only so much energy to give. When it feeds the table, the energy is used up sooner, so the loud sound fades away faster than the quiet one would have.

Questions

  1. What do you hear when you hold a struck tuning fork in the air? in the text

  2. Why do the prongs of the fork push very little air? in the text

  3. What happens to the tabletop when the fork's handle touches it? in the text

  4. Which part of a guitar does the same job as the table? in the text

  5. Why does the loud sound from the fork on a table fade away faster? think about it

  6. Why do you think a guitar string held by itself sounds so quiet? think about it

Words to know

tuning fork
a metal tool with two prongs that makes one pure note
vibrating
moving back and forth very quickly
prongs
the long, thin parts of a fork
loudspeaker
a device that makes sound louder
hollow
empty on the inside
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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 · 208 words · Flesch-Kincaid grade 2.6

Strike a tuning fork on your knee. Hold it in the air. You hear a faint, pure note. Now touch the end of the handle to a tabletop. The sound gets much louder. It is as if someone turned up a volume knob. Nothing was added to the fork. So what changed?

Every sound starts with something vibrating. The two thin prongs of the fork swing back and forth many times each second. But the prongs are narrow. They push very little air with each swing. Your ear gets only a weak signal.

A tabletop is big and flat. When the handle touches it, the shaking goes into the wood. The whole surface shakes a little. A big surface pushes on much more air than a thin prong. So it sends out a stronger sound wave. The table works like a loudspeaker for the fork.

Instruments use the same idea. A guitar string alone is quiet. It passes its shaking to the hollow wooden body. The body shakes too and fills the room. But there is a catch. The fork has only so much energy. When it feeds the table, the energy is used up sooner. So the loud sound fades faster than the quiet one would have.

▲ This passage · 226 words · Flesch-Kincaid grade 4.9

Strike a tuning fork on your knee and hold it in the air. You will hear a faint, pure note. Now touch the end of its handle to a tabletop. Suddenly the sound gets much louder, as if someone had turned up a volume knob. Nothing was added to the fork, so what changed?

Every sound begins with something vibrating. The two thin prongs of the fork swing back and forth many times each second. But prongs are narrow, so they push very little air with each swing, and your ear receives only a weak signal.

A tabletop is large and flat. When the fork's handle touches it, the vibrations travel into the wood and make the whole surface shake a little. Because a big surface pushes on much more air than a thin prong does, it sends out a stronger sound wave. The table is working like a loudspeaker for the fork.

Musical instruments use the same idea. The strings of a guitar make only a quiet sound alone. They pass their vibrations to the hollow wooden body, which shakes along with them and fills the room. There is a catch, however. The fork has only so much energy to give. When it feeds the table, the energy is used up sooner, so the loud sound fades away faster than the quiet one would have.

■ Harder · 253 words · Flesch-Kincaid grade 6

Strike a tuning fork against your knee and hold it up in the open air, and you will hear a faint, pure note. Now touch the end of its handle to a tabletop. Suddenly the sound swells to a much louder level, as if someone had turned up a volume knob. Nothing was added to the fork itself, so what could have changed?

Every sound begins with something vibrating. The two thin prongs of the fork swing back and forth many times each second. However, the prongs are very narrow, so they push only a tiny amount of air with each swing, and your ear receives just a weak signal.

A tabletop, by contrast, is large and flat. When the fork's handle touches it, the vibrations travel into the wood and cause the entire surface to shake a little. Because a big surface pushes on far more air than a thin prong does, it sends out a much stronger sound wave. In effect, the table works like a loudspeaker for the fork.

Musical instruments rely on the same principle. The strings of a guitar produce only a quiet sound on their own. They pass their vibrations along to the hollow wooden body, which shakes in sympathy with them and fills the whole room with sound. There is a catch, however. The fork has only so much energy to give. When it feeds the table, that energy is used up sooner, so the loud sound fades away faster than the quiet one would have.

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 tuning fork, vibrating, prongs, loudspeaker and hollow 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 "Why a Humming Fork Gets Louder on a Table"?

It was written for 6th grade. It has 226 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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