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Four Ropes Make a Heavy Crate Feel Light

5th grade nonfiction passage about block and tackle pulleys: 219 words, six questions, an answer key and vocabulary.

5th grade nonfiction block and tackle pulleys 219 words

Four Ropes Make a Heavy Crate Feel Light

Suppose you need to lift a heavy crate off the ground. You could tug on a single rope, but your arms would soon give out. A set of pulleys called a block and tackle can make the same job far easier.

A pulley is a wheel with a groove around its edge, and a rope rides in that groove. In a block and tackle, several pulleys are grouped into two blocks. One block is fixed to a beam overhead. The other is attached to the load. A single long rope loops back and forth between the two blocks.

Here is the trick. The weight of the crate is shared by every length of rope that holds up the moving block. If four lengths of rope hold it up, each one carries about a quarter of the weight. So the person pulling needs only about a quarter of the force the crate would normally need.

There is a trade, though. To raise the crate one foot, you must pull four feet of rope through the pulleys. You use less force, but you pull over a longer distance. This trade shows up in many simple machines.

Sailors, builders, and mechanics have all used this idea. Cranes and boat rigging depend on it, and so do many gym machines that use cables.

Questions

  1. What is a pulley? in the text

  2. How many blocks are in a block and tackle? in the text

  3. If four lengths of rope hold the load, about how much weight does each carry? in the text

  4. What must you give up to use less force? in the text

  5. Why does pulling feel easier with more ropes holding the crate? think about it

  6. Why would a boat crew find a block and tackle useful? think about it

Words to know

pulley
a wheel with a groove that guides a rope
groove
a long, narrow channel cut into something
load
the weight that a machine has to move
overhead
above your head
rigging
the ropes and gear that handle a ship's sails
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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 · 158 words · Flesch-Kincaid grade 1

Say you must lift a heavy crate. You could pull on one rope. Your arms would get tired fast. A set of pulleys can help. It is called a block and tackle.

A pulley is a wheel with a groove. A rope rides in the groove. A block and tackle has two blocks of pulleys. One block hangs from a beam above. The other is tied to the load. One long rope loops back and forth between them.

Here is the trick. Every rope that holds up the load shares its weight. Say four ropes hold it up. Then each rope carries about a quarter of the weight. You need only about a quarter of the pull.

But there is a trade. To lift the crate one foot, you pull four feet of rope. You use less force, but you pull farther. Many simple machines work this way.

Sailors and builders use this idea. Cranes use it too.

▲ This passage · 219 words · Flesch-Kincaid grade 3.7

Suppose you need to lift a heavy crate off the ground. You could tug on a single rope, but your arms would soon give out. A set of pulleys called a block and tackle can make the same job far easier.

A pulley is a wheel with a groove around its edge, and a rope rides in that groove. In a block and tackle, several pulleys are grouped into two blocks. One block is fixed to a beam overhead. The other is attached to the load. A single long rope loops back and forth between the two blocks.

Here is the trick. The weight of the crate is shared by every length of rope that holds up the moving block. If four lengths of rope hold it up, each one carries about a quarter of the weight. So the person pulling needs only about a quarter of the force the crate would normally need.

There is a trade, though. To raise the crate one foot, you must pull four feet of rope through the pulleys. You use less force, but you pull over a longer distance. This trade shows up in many simple machines.

Sailors, builders, and mechanics have all used this idea. Cranes and boat rigging depend on it, and so do many gym machines that use cables.

■ Harder · 227 words · Flesch-Kincaid grade 6.1

Suppose you need to raise a heavy crate off the ground. You could simply tug on a single rope, but your arms would soon give out from the strain. A system of pulleys known as a block and tackle can make the same task dramatically easier.

A pulley is a wheel with a groove around its rim, and a rope rides inside that groove. In a block and tackle, several pulleys are grouped into two separate blocks. One block is fastened to a sturdy beam overhead, while the other is attached to the load itself. A single long rope loops back and forth between the two blocks.

Here is the clever part. The weight of the crate is divided among every length of rope supporting the moving block. If four lengths of rope hold it up, each carries only about a quarter of the weight, so the person pulling needs just a quarter of the force the crate would otherwise demand.

There is a trade, however. To raise the crate a single foot, you must draw four feet of rope through the pulleys. You use less force, but you pull across a longer distance, and that exchange appears in many simple machines.

Sailors, builders, and mechanics have all relied on this principle. Cranes and boat rigging depend on it, as do many gym machines that use cables.

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 pulley, groove, load, overhead and rigging 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 "Four Ropes Make a Heavy Crate Feel Light"?

It was written for 5th grade. It has 219 words and works out to a Flesch-Kincaid grade level of about 3.7. 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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