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Why Arches Hold Up Bridges

4th grade nonfiction passage about arch bridges: 223 words, six questions, an answer key and vocabulary.

4th grade nonfiction arch bridges 223 words

Why Arches Hold Up Bridges

Some of the oldest bridges in the world are made of stone, and some of them are still standing. Many have the same shape. They rise in a curve, called an arch. Why is an arch so strong?

Think about how a flat stone slab works. If you lay it across a gap, its weight and anything on top pulls the middle downward, and the slab can crack. An arch solves the problem in a different way. The stones in an arch are shaped a little like wedges, thick at the top and thin at the bottom. They lean against one another. Weight that falls on the arch does not just push straight down. It travels along the curve to the two ends.

At each end of the arch, there is a solid block of stone or ground called an abutment. The abutments push back, which keeps the ends from spreading apart. At the very top sits the keystone, the last stone to be placed. It locks the others in place.

Builders long ago used wooden frames to hold the stones until the keystone went in. Once it was in, the frame was no longer needed, because the arch held itself up. The Romans built many arches, for bridges and for channels that carried water, and some of them are still in use.

Questions

  1. What is the curved shape of many old stone bridges called? in the text

  2. What can happen to a flat stone slab laid across a gap? in the text

  3. Where does weight on an arch travel? in the text

  4. What is the stone at the top of an arch called? in the text

  5. What did builders use to hold the stones until the keystone went in? in the text

  6. Why do the abutments matter to an arch? think about it

Words to know

arch
a curved shape that holds up weight over an open space
slab
a thick, flat piece of stone or other hard material
abutment
a solid support at the end of an arch or bridge
keystone
the center stone at the top of an arch that locks the others in place
frames
structures made of pieces joined together to hold something up
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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 · 172 words · Flesch-Kincaid grade 1.5

Some of the oldest bridges are made of stone. Some still stand. Many have the same shape, a curve called an arch. Why is an arch so strong?

Think of a flat stone slab laid over a gap. Its weight pulls the middle down. The slab can crack. An arch works in a different way. Its stones are shaped like wedges, thick at the top and thin at the bottom. They lean on one another. Weight on the arch does not push straight down. It travels along the curve to the two ends.

At each end is a block of stone or ground called an abutment. It pushes back. This keeps the ends from spreading apart. At the top is the keystone. It is the last stone put in. It locks the others in place.

Builders used wooden frames to hold the stones up until the keystone went in. Then the arch held itself up. The Romans built many arches for bridges and for channels that carried water. Some are still used.

▲ This passage · 223 words · Flesch-Kincaid grade 3.5

Some of the oldest bridges in the world are made of stone, and some of them are still standing. Many have the same shape. They rise in a curve, called an arch. Why is an arch so strong?

Think about how a flat stone slab works. If you lay it across a gap, its weight and anything on top pulls the middle downward, and the slab can crack. An arch solves the problem in a different way. The stones in an arch are shaped a little like wedges, thick at the top and thin at the bottom. They lean against one another. Weight that falls on the arch does not just push straight down. It travels along the curve to the two ends.

At each end of the arch, there is a solid block of stone or ground called an abutment. The abutments push back, which keeps the ends from spreading apart. At the very top sits the keystone, the last stone to be placed. It locks the others in place.

Builders long ago used wooden frames to hold the stones until the keystone went in. Once it was in, the frame was no longer needed, because the arch held itself up. The Romans built many arches, for bridges and for channels that carried water, and some of them are still in use.

■ Harder · 233 words · Flesch-Kincaid grade 5.9

Some of the oldest bridges in the world are built of stone, and a number of them are still standing today. Many share the same distinctive shape, rising in a curve known as an arch. Why is an arch so remarkably strong?

Consider how a flat stone slab behaves. If you lay it across a gap, its own weight and anything placed on top pulls the middle downward, and the slab can crack. An arch solves the problem in an entirely different way. The stones in an arch are shaped somewhat like wedges, thick at the top and thin at the bottom, and they lean against one another. Weight that falls on the arch does not simply push straight down. Instead, it travels along the curve toward the two ends.

At each end of the arch stands a solid block of stone or ground called an abutment. The abutments push back, which prevents the ends from spreading apart. At the very top sits the keystone, the last stone to be placed, which locks all of the others firmly in place.

Builders long ago used wooden frames to support the stones until the keystone was set. Once it was in position, the frame was no longer needed, because the arch held itself up. The Romans constructed many arches, both for bridges and for channels that carried water, and some of them remain in use.

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 arch, slab, abutment, keystone and frames 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 6 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 "Why Arches Hold Up Bridges"?

It was written for 4th grade. It has 223 words and works out to a Flesch-Kincaid grade level of about 3.5. 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. 5 ask for something the text says directly and 1 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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