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How a Thermos Keeps Drinks Hot

6th grade nonfiction passage about heat transfer: 219 words, five questions, an answer key and vocabulary.

6th grade nonfiction heat transfer 219 words

How a Thermos Keeps Drinks Hot

A good thermos can keep soup steaming for hours on a cold hiking trail, and it can keep lemonade icy on a hot afternoon. To see how it works, it helps to know that heat always moves from warmer things toward cooler things, and that it travels in three ways.

Conduction is heat passing through touching materials, such as the handle of a spoon warming up in hot soup. Convection is heat carried by moving liquids or gases, like warm air rising above a radiator. Radiation is heat that travels as invisible waves, the way sunshine warms your face across empty space. A thermos is built to block all three.

The bottle has two walls with a gap between them. Most of the air has been pumped out of that gap, which makes a vacuum. With almost nothing in the gap, there is little to carry heat by conduction or convection. The inner wall is also coated with a shiny layer that reflects radiation, much as a mirror bounces back light. Finally, a tight stopper keeps warm air from escaping at the top.

The design was invented by a Scottish scientist, James Dewar, in 1892. A thermos does not make anything hot or cold. It simply slows heat down so that your drink stays near its original temperature far longer.

Questions

  1. What are the three ways that heat travels? in the text

  2. What is in the gap between the two walls of a thermos? in the text

  3. What does the shiny coating on the inner wall do? in the text

  4. Why does a thermos help keep lemonade cold on a hot day? think about it

  5. Why is a vacuum good at stopping heat from passing through the gap? think about it

Words to know

conduction
heat moving through materials that touch
convection
heat carried by moving liquids or gases
radiation
heat that travels as invisible waves
vacuum
a space with almost no air or matter in it
reflects
bounces back instead of passing through
stopper
a plug that closes the top of a bottle
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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 · 191 words · Flesch-Kincaid grade 3.7

A good thermos can keep soup steaming for hours on a cold trail. It can keep lemonade icy on a hot day. To see how, you need to know a fact. Heat always moves from warmer things toward cooler things. It travels in three ways.

Conduction is heat passing through things that touch. A spoon handle warms up in hot soup. Convection is heat carried by moving liquids or gases. Warm air rises above a radiator. Radiation is heat that travels as invisible waves. Sunshine warms your face across empty space. A thermos blocks all three.

The bottle has two walls with a gap between them. Most of the air is pumped out of the gap. That makes a vacuum. With almost nothing in the gap, little heat can move by conduction or convection. The inner wall has a shiny coating. It reflects radiation like a mirror bounces back light. A tight stopper keeps warm air from escaping at the top.

A Scottish scientist, James Dewar, invented it in 1892. A thermos does not make anything hot or cold. It slows heat down. Your drink stays near its first temperature much longer.

▲ This passage · 219 words · Flesch-Kincaid grade 6.9

A good thermos can keep soup steaming for hours on a cold hiking trail, and it can keep lemonade icy on a hot afternoon. To see how it works, it helps to know that heat always moves from warmer things toward cooler things, and that it travels in three ways.

Conduction is heat passing through touching materials, such as the handle of a spoon warming up in hot soup. Convection is heat carried by moving liquids or gases, like warm air rising above a radiator. Radiation is heat that travels as invisible waves, the way sunshine warms your face across empty space. A thermos is built to block all three.

The bottle has two walls with a gap between them. Most of the air has been pumped out of that gap, which makes a vacuum. With almost nothing in the gap, there is little to carry heat by conduction or convection. The inner wall is also coated with a shiny layer that reflects radiation, much as a mirror bounces back light. Finally, a tight stopper keeps warm air from escaping at the top.

The design was invented by a Scottish scientist, James Dewar, in 1892. A thermos does not make anything hot or cold. It simply slows heat down so that your drink stays near its original temperature far longer.

■ Harder · 240 words · Flesch-Kincaid grade 8.8

A well-made thermos can keep soup steaming for hours on a frigid hiking trail, and it can keep lemonade icy throughout a sweltering afternoon. To understand how it accomplishes this, it helps to know that heat always moves from warmer objects toward cooler ones, and that it travels in three distinct ways.

Conduction is heat passing through materials that touch one another, such as the handle of a spoon gradually warming up in hot soup. Convection is heat carried by moving liquids or gases, like warm air rising above a radiator. Radiation is heat that travels as invisible waves, in the same way that sunshine warms your face across the emptiness of space. A thermos is engineered to block all three.

The bottle consists of two walls separated by a narrow gap. Nearly all of the air has been pumped out of that gap, which creates a vacuum. With almost nothing inside the gap, there is very little to carry heat by conduction or convection. The inner wall is also coated with a shiny layer that reflects radiation, much as a mirror bounces back light. Finally, a tight stopper prevents warm air from escaping at the top.

The design was invented by a Scottish scientist named James Dewar in 1892. A thermos does not actually make anything hot or cold. It merely slows the movement of heat so that your drink remains close to its original temperature for far longer.

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 conduction, convection, radiation, vacuum, reflects and stopper 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 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 a Thermos Keeps Drinks Hot"?

It was written for 6th grade. It has 219 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 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 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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