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The Wood Frog That Freezes Solid Each Winter

7th grade nonfiction passage about wood frogs and winter: 227 words, six questions, an answer key and vocabulary.

7th grade nonfiction wood frogs and winter 227 words

The Wood Frog That Freezes Solid Each Winter

Winter is a hard season for any animal that cannot make its own body heat. A wood frog, which lives in forests across much of North America, has no burrow deep enough to escape the cold. Instead it settles under a blanket of fallen leaves and does something that sounds impossible. It allows itself to freeze.

As the temperature falls, ice begins to form in the spaces between the frog's cells and under its skin. Its heart stops beating and its breathing stops. To a person who found it, the frog would look like a small, stiff lump of ice. Yet it is still alive, waiting.

The secret lies in what happens inside the body just before the freeze. The frog's liver releases large amounts of glucose, a kind of sugar, into the blood. This sugar works somewhat like the antifreeze in a car. It stays inside the cells and keeps them from freezing, which protects them from damage that ice crystals would cause.

When spring arrives, the process runs in reverse. The ice melts from the inside outward, the heart starts beating again, and the frog begins to breathe. Within a day or two it is hopping around and looking for a pond. Wood frogs are among the first amphibians to call and mate each year, ready to begin again as soon as the world thaws.

Questions

  1. Where does a wood frog spend the winter? in the text

  2. What happens to the frog's heart and breathing when it freezes? in the text

  3. What does the frog's liver release before the freeze? in the text

  4. What happens to the frog when spring arrives? in the text

  5. Why does the passage compare glucose to car antifreeze? think about it

  6. Why does the writer say the frog is still alive even though it looks like ice? think about it

Words to know

burrow
a hole or tunnel an animal digs to live in
glucose
a simple sugar that gives living things energy
antifreeze
a liquid added to stop water from freezing
crystals
tiny hard pieces with sharp edges, such as ice
amphibians
animals such as frogs that live in water and on land
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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 · 192 words · Flesch-Kincaid grade 2.4

Winter is hard for animals that cannot make their own heat. The wood frog lives in forests across much of North America. It has no burrow deep enough to escape the cold. So it settles under fallen leaves. Then it does something that sounds impossible. It lets itself freeze.

As the air gets colder, ice forms between the frog's cells and under its skin. Its heart stops. Its breathing stops. If a person found it, the frog would look like a stiff lump of ice. But it is still alive.

The secret is in what the body does just before the freeze. The frog's liver sends lots of glucose, a kind of sugar, into the blood. The sugar works like the antifreeze in a car. It stays in the cells and keeps them from freezing. This protects them from the harm that ice crystals could do.

In spring, the process runs backward. The ice melts. The heart starts to beat again. The frog starts to breathe. In a day or two it is hopping and looking for a pond. Wood frogs are among the first frogs to call and mate each year.

▲ This passage · 227 words · Flesch-Kincaid grade 5.9

Winter is a hard season for any animal that cannot make its own body heat. A wood frog, which lives in forests across much of North America, has no burrow deep enough to escape the cold. Instead it settles under a blanket of fallen leaves and does something that sounds impossible. It allows itself to freeze.

As the temperature falls, ice begins to form in the spaces between the frog's cells and under its skin. Its heart stops beating and its breathing stops. To a person who found it, the frog would look like a small, stiff lump of ice. Yet it is still alive, waiting.

The secret lies in what happens inside the body just before the freeze. The frog's liver releases large amounts of glucose, a kind of sugar, into the blood. This sugar works somewhat like the antifreeze in a car. It stays inside the cells and keeps them from freezing, which protects them from damage that ice crystals would cause.

When spring arrives, the process runs in reverse. The ice melts from the inside outward, the heart starts beating again, and the frog begins to breathe. Within a day or two it is hopping around and looking for a pond. Wood frogs are among the first amphibians to call and mate each year, ready to begin again as soon as the world thaws.

■ Harder · 233 words · Flesch-Kincaid grade 8.2

Winter is an especially punishing season for any animal that cannot generate its own body heat. The wood frog, which inhabits forests across much of North America, has no burrow deep enough to escape the cold. Instead, it settles beneath a blanket of fallen leaves and then does something that sounds impossible: it allows itself to freeze.

As the temperature drops, ice begins to form in the spaces between the frog's cells and beneath its skin. Its heart stops beating and its breathing ceases entirely. To a person who happened upon it, the frog would look like a small, stiff lump of ice. Nevertheless, it remains alive, simply waiting.

The secret lies in what happens inside the body just before the freeze. The frog's liver releases large quantities of glucose, a type of sugar, into its bloodstream. This sugar functions rather like the antifreeze in a car, staying inside the cells and preventing them from freezing, which shields them from the damage that ice crystals would otherwise inflict.

When spring finally arrives, the process runs in reverse. The ice melts from the inside outward, the heart resumes its beating, and the frog begins to breathe once more. Within a day or two it is hopping about in search of a pond. Wood frogs are among the first amphibians to call and mate each year, ready to start over the moment the world thaws.

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 burrow, glucose, antifreeze, crystals and amphibians 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 "The Wood Frog That Freezes Solid Each Winter"?

It was written for 7th grade. It has 227 words and works out to a Flesch-Kincaid grade level of about 5.8. 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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