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How Bats Find Their Way

8th grade nonfiction passage about animals and sound: 282 words, five questions, an answer key and vocabulary.

8th grade nonfiction animals and sound 282 words

How Bats Find Their Way

Bats are famous for flying at night, but most of them are not blind. Their eyes work quite well, yet in complete darkness, eyesight alone is not enough to catch a flying insect. Many bats navigate and hunt with a remarkable skill called echolocation, which lets them build a picture of their surroundings from sound.

The process begins with sound. A bat makes a rapid series of very high-pitched calls, which are usually too high for human ears to hear. Each call travels outward as a sound wave. When the wave strikes an object, such as a tree branch or a flying moth, part of it bounces back as an echo. The bat's large, sensitive ears catch the echo, and its brain compares it with the call that was sent.

The echo reveals a surprising amount of information. The time between the call and the echo tells the bat how far away the object is, because sound travels at a steady speed. A longer delay means the object is farther away. Differences in the echo's pitch and loudness help the bat judge the size, shape, and even the texture of what it has found. If the object is a moth that is moving, the echo also shows which way it is flying.

As a bat closes in on its prey, it speeds up its calls, sometimes making more than one hundred each second in the final moments of a chase. This gives the bat a rapid stream of updates so it can adjust its path. Many bats eat enormous numbers of insects, including pests that damage crops, which makes them valuable neighbors for farmers, who benefit from this natural pest control.

Questions

  1. What is echolocation? in the text

  2. What does a bat's ear catch after it makes a call? in the text

  3. How does a bat learn how far away an object is? in the text

  4. Why does a longer delay mean that an object is farther away? think about it

  5. Why are bats valuable neighbors for farmers? think about it

Words to know

echolocation
finding things by sending out sounds and listening for echoes
navigate
to find your way from place to place
pitch
how high or low a sound is
echo
a sound that bounces back after hitting something
texture
how the surface of something feels or looks
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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 · 257 words · Flesch-Kincaid grade 2.7

Bats are famous for flying at night, but most of them are not blind. Their eyes work well. Still, in the dark, eyesight is not enough. Many bats find their way and hunt with a skill called echolocation. It lets them build a picture of their world from sound.

Here is how it works. A bat makes a series of very high calls. They are usually too high for people to hear. Each call travels out as a sound wave. The wave hits an object, such as a branch or a flying moth. Part of the wave bounces back as an echo. The bat's big, sensitive ears catch the echo. Its brain compares the echo with the call it sent.

The echo tells the bat a lot. The time between the call and the echo shows how far away the object is. Sound travels at a steady speed. So a longer delay means the object is farther away. The pitch and loudness of the echo help the bat judge the size, shape, and even the texture of the object. If the object is a moving moth, the echo also shows which way it is flying.

When a bat gets close to its prey, it makes its calls faster. In the last moments of a chase, it may make more than one hundred calls each second. This gives the bat quick updates, so it can change its path. Many bats eat huge numbers of insects. Some are pests that harm crops. So bats are good neighbors for farmers.

▲ This passage · 282 words · Flesch-Kincaid grade 7.1

Bats are famous for flying at night, but most of them are not blind. Their eyes work quite well, yet in complete darkness, eyesight alone is not enough to catch a flying insect. Many bats navigate and hunt with a remarkable skill called echolocation, which lets them build a picture of their surroundings from sound.

The process begins with sound. A bat makes a rapid series of very high-pitched calls, which are usually too high for human ears to hear. Each call travels outward as a sound wave. When the wave strikes an object, such as a tree branch or a flying moth, part of it bounces back as an echo. The bat's large, sensitive ears catch the echo, and its brain compares it with the call that was sent.

The echo reveals a surprising amount of information. The time between the call and the echo tells the bat how far away the object is, because sound travels at a steady speed. A longer delay means the object is farther away. Differences in the echo's pitch and loudness help the bat judge the size, shape, and even the texture of what it has found. If the object is a moth that is moving, the echo also shows which way it is flying.

As a bat closes in on its prey, it speeds up its calls, sometimes making more than one hundred each second in the final moments of a chase. This gives the bat a rapid stream of updates so it can adjust its path. Many bats eat enormous numbers of insects, including pests that damage crops, which makes them valuable neighbors for farmers, who benefit from this natural pest control.

■ Harder · 295 words · Flesch-Kincaid grade 9.8

Bats are famous for flying after dark, yet the majority of them are not blind at all. Their eyes function perfectly well, but in the darkness, eyesight alone is insufficient. Many species navigate and hunt using a remarkable ability called echolocation, which enables them to construct a detailed picture of their surroundings from sound.

The process works as follows. A bat emits a rapid series of extremely high-pitched calls, which are usually pitched too high for human ears to detect. Each call travels outward as a sound wave. When the wave strikes an object, such as a tree branch or a flying moth, part of it bounces back as an echo. The bat's large, sensitive ears capture the echo, and its brain compares it with the call that was originally sent.

The echo reveals an astonishing amount of information. The interval between the call and the echo tells the bat how far away the object is, because sound travels at a steady speed, so a longer delay indicates a greater distance. Differences in the echo's pitch and loudness help the bat judge the size, shape, and even the texture of whatever it has located. If the object is a moth in motion, the echo also reveals the direction in which it is flying.

As a bat closes in on its prey, it accelerates its calls, sometimes producing more than one hundred each second during the final moments of a chase. This provides the bat with a rapid stream of updates so that it can adjust its path. Many bats consume enormous numbers of insects, including pests that damage crops, which makes them extremely valuable neighbors for farmers, who benefit greatly from this natural form of pest control, since fewer pests means fewer damaged plants.

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 echolocation, navigate, pitch, echo and texture 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 Bats Find Their Way"?

It was written for 8th grade. It has 282 words and works out to a Flesch-Kincaid grade level of about 7.1. 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 five. 3 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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