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The Cold Spots Inside a Microwave Oven

6th grade nonfiction passage about microwaves and heating: 235 words, six questions, an answer key and vocabulary.

6th grade nonfiction microwaves and heating 235 words

The Cold Spots Inside a Microwave Oven

Leftover pasta comes out of the microwave steaming at the edge and cold in the middle. Almost everyone has seen it. The reason has to do with the way a microwave oven actually works.

Inside the oven, a part called a magnetron produces microwaves, which are invisible waves of energy, a bit like radio waves. The waves bounce around the metal walls of the oven and move into the food. Water molecules in the food absorb this energy and start to jiggle faster. Faster jiggling means more heat, and the heat then spreads to nearby parts of the food.

The waves do not fill the oven evenly. Where they bounce and overlap, some spots get strong waves and some get weak ones, like the hills and valleys of ripples on a pond. A plate left sitting still might have a hot spot in one place and a cold spot in another. That is why most microwaves have a turntable. As the plate turns, the food moves through the strong and weak spots, which evens out the heating.

You can help, too. Stirring food halfway through spreads the heat around. Letting it rest for a minute afterward gives the warm parts time to share their heat with the cool parts. Foods with little water, such as a dry cracker, heat up less than a bowl of soup, because there is less water to absorb the waves.

Questions

  1. What part of the oven produces microwaves? in the text

  2. What do water molecules do when they absorb the energy of the waves? in the text

  3. What does a turntable do for the food? in the text

  4. What are two things a person can do to help food heat evenly? in the text

  5. Why does a bowl of soup heat up more than a dry cracker? think about it

  6. Why might a cold spot appear in pasta even while the oven is running? think about it

Words to know

magnetron
the part of a microwave oven that makes microwaves
absorb
to soak up or take in
molecules
the tiny particles that everything is made of
turntable
a flat plate that spins around slowly
overlap
to lie partly on top of each other
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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 · 207 words · Flesch-Kincaid grade 2.6

Leftover pasta comes out of the microwave. The edge is steaming. The middle is cold. Almost everyone has seen this. The reason is in how a microwave works.

Inside the oven, a part called a magnetron makes microwaves. These are invisible waves of energy, a bit like radio waves. The waves bounce off the metal walls and go into the food. Water molecules in the food take in the energy. They start to jiggle faster. Faster jiggling makes heat. Then the heat spreads to nearby parts of the food.

The waves do not fill the oven evenly. Where they bounce and overlap, some spots get strong waves and some get weak waves. It is like ripples on a pond. A plate that sits still may have a hot spot in one place and a cold spot in another. That is why most microwaves have a turntable. The plate turns. The food moves through the strong and weak spots. The heat gets more even.

You can help too. Stir the food halfway through. Let it rest for a minute after. The warm parts share heat with the cool parts. Dry foods, like a cracker, heat up less than soup. They have less water to take in the waves.

▲ This passage · 235 words · Flesch-Kincaid grade 5.8

Leftover pasta comes out of the microwave steaming at the edge and cold in the middle. Almost everyone has seen it. The reason has to do with the way a microwave oven actually works.

Inside the oven, a part called a magnetron produces microwaves, which are invisible waves of energy, a bit like radio waves. The waves bounce around the metal walls of the oven and move into the food. Water molecules in the food absorb this energy and start to jiggle faster. Faster jiggling means more heat, and the heat then spreads to nearby parts of the food.

The waves do not fill the oven evenly. Where they bounce and overlap, some spots get strong waves and some get weak ones, like the hills and valleys of ripples on a pond. A plate left sitting still might have a hot spot in one place and a cold spot in another. That is why most microwaves have a turntable. As the plate turns, the food moves through the strong and weak spots, which evens out the heating.

You can help, too. Stirring food halfway through spreads the heat around. Letting it rest for a minute afterward gives the warm parts time to share their heat with the cool parts. Foods with little water, such as a dry cracker, heat up less than a bowl of soup, because there is less water to absorb the waves.

■ Harder · 253 words · Flesch-Kincaid grade 8.4

Leftover pasta often comes out of the microwave steaming around the edge yet still cold in the middle. Almost everyone has encountered this frustrating result at some point. The explanation lies in the way a microwave oven actually works.

Inside the oven, a component called a magnetron produces microwaves, which are invisible waves of energy somewhat similar to radio waves. The waves bounce around the metal walls of the oven and then travel into the food. Water molecules in the food absorb this energy and begin to jiggle faster. Faster jiggling means more heat, and that heat gradually spreads to the neighboring parts of the food.

However, the waves do not fill the oven evenly. Where they bounce and overlap, some spots receive strong waves while others receive weak ones, much like the hills and valleys of ripples on a pond. A plate left sitting perfectly still might develop a hot spot in one place and a cold spot in another. That is why most microwave ovens include a turntable. As the plate slowly turns, the food travels through the strong and weak spots, which evens out the heating.

You can also help the process along. Stirring the food halfway through spreads the heat around, and letting it rest for a minute afterward gives the warm parts time to share their heat with the cooler parts. Foods containing little water, such as a dry cracker, heat up less than a bowl of soup, because there is less water available to absorb the waves.

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 magnetron, absorb, molecules, turntable and overlap 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 Cold Spots Inside a Microwave Oven"?

It was written for 6th grade. It has 235 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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