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Salt Squeezed Out of Freezing Seawater

8th grade nonfiction passage about sea ice and brine: 250 words, six questions, an answer key and vocabulary.

8th grade nonfiction sea ice and brine 250 words

Salt Squeezed Out of Freezing Seawater

When seawater freezes, you might expect to get frozen salt water. Instead, something more interesting happens. As ice crystals form, they leave most of the salt behind. The ice that results is much less salty than the water it came from, which is why melted sea ice is far better to drink than seawater, though it is still not perfectly fresh.

The salt does not vanish. It collects in the liquid water between the growing crystals. This leftover water is called brine, and it is saltier than ordinary seawater. Because salt lowers the temperature at which water freezes, the brine stays liquid even when the ice around it is quite cold. It is trapped in a network of tiny channels and pockets inside the ice, like water in a sponge.

Over time, some of the brine drains out of the bottom of the ice. Because it is salty and dense, it sinks into the sea below in thin streams. In the polar oceans this sinking water helps drive currents that carry cold water through the deep ocean.

The channels also matter to living things. Tiny algae and bacteria live inside the brine, and in spring the algae grow when sunlight passes through the ice. Small animals graze on them along the ice's underside, which feeds a food chain that reaches seals and seabirds. So what looks like a lifeless white sheet is actually a layered habitat, shaped by the way salt is squeezed out when the sea turns to ice.

Questions

  1. What happens to most of the salt when seawater freezes? in the text

  2. What is brine? in the text

  3. Why does the brine stay liquid even in cold ice? in the text

  4. Where do tiny algae and bacteria live in sea ice? in the text

  5. Why does brine that drains from the ice sink into the sea below? think about it

  6. Why is sea ice called a layered habitat instead of a lifeless sheet? think about it

Words to know

crystals
tiny solid pieces with flat sides, like the pieces of ice
brine
very salty water
channels
narrow paths that liquid can flow through
dense
heavy for its size, with its parts packed closely together
habitat
the natural home of a plant or animal
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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 · 229 words · Flesch-Kincaid grade 4.4

When seawater freezes, you might think you get frozen salt water. But something more interesting happens. As ice crystals form, they leave most of the salt behind. The ice is much less salty than the sea. Melted sea ice is far better to drink than seawater, but it is still not perfectly fresh.

The salt does not vanish. It collects in the liquid water between the growing crystals. This water is called brine, and it is saltier than seawater. Salt lowers the temperature at which water freezes. So the brine stays liquid even when the ice around it is cold. It is trapped in tiny channels and pockets inside the ice, like water in a sponge.

Over time, some brine drains out of the bottom of the ice. It is salty and dense, so it sinks into the sea in thin streams. In the polar oceans, this sinking water helps drive currents that carry cold water through the deep ocean.

The channels matter to living things too. Tiny algae and bacteria live in the brine. In spring, the algae grow when sunlight passes through the ice. Small animals graze on them under the ice. This feeds a food chain that reaches seals and seabirds. So sea ice is not a lifeless white sheet. It is a layered home for living things, shaped by the way salt is squeezed out.

▲ This passage · 250 words · Flesch-Kincaid grade 6.9

When seawater freezes, you might expect to get frozen salt water. Instead, something more interesting happens. As ice crystals form, they leave most of the salt behind. The ice that results is much less salty than the water it came from, which is why melted sea ice is far better to drink than seawater, though it is still not perfectly fresh.

The salt does not vanish. It collects in the liquid water between the growing crystals. This leftover water is called brine, and it is saltier than ordinary seawater. Because salt lowers the temperature at which water freezes, the brine stays liquid even when the ice around it is quite cold. It is trapped in a network of tiny channels and pockets inside the ice, like water in a sponge.

Over time, some of the brine drains out of the bottom of the ice. Because it is salty and dense, it sinks into the sea below in thin streams. In the polar oceans this sinking water helps drive currents that carry cold water through the deep ocean.

The channels also matter to living things. Tiny algae and bacteria live inside the brine, and in spring the algae grow when sunlight passes through the ice. Small animals graze on them along the ice's underside, which feeds a food chain that reaches seals and seabirds. So what looks like a lifeless white sheet is actually a layered habitat, shaped by the way salt is squeezed out when the sea turns to ice.

■ Harder · 268 words · Flesch-Kincaid grade 8.2

When seawater freezes, one might reasonably expect the result to be frozen salt water. Instead, something far more interesting occurs. As ice crystals form, they leave the majority of the salt behind. The ice that results is considerably less salty than the water from which it came, which is why melted sea ice is much better to drink than seawater, although it still is not perfectly fresh.

The salt does not simply disappear. It collects in the liquid water lying between the growing crystals. This leftover water is called brine, and it is saltier than ordinary seawater. Because salt lowers the temperature at which water freezes, the brine remains liquid even when the surrounding ice is quite cold. It becomes trapped in a network of tiny channels and pockets within the ice, much like water held in a sponge.

As time passes, some of the brine drains out of the underside of the ice. Because it is both salty and dense, it sinks into the sea below in thin streams. In the polar oceans, this sinking water helps to drive currents that carry cold water through the deep ocean.

The channels are also important to living things. Tiny algae and bacteria make their home inside the brine, and in spring the algae flourish when sunlight passes through the ice. Small animals graze on them along the ice's underside, which supports a food chain that eventually reaches seals and seabirds. What appears to be a lifeless white sheet is therefore a layered habitat, shaped by the manner in which salt is squeezed out when the sea turns to ice.

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 crystals, brine, channels, dense and habitat 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 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 "Salt Squeezed Out of Freezing Seawater"?

It was written for 8th grade. It has 250 words and works out to a Flesch-Kincaid grade level of about 6.9. 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 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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