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From Wild Grass to Corn on the Cob

8th grade nonfiction passage about how corn was bred from teosinte: 269 words, six questions, an answer key and vocabulary.

8th grade nonfiction how corn was bred from teosinte 269 words

From Wild Grass to Corn on the Cob

Corn, also called maize, feeds people and animals all over the world, yet its wild ancestor looks nothing like the cobs in a grocery store. The ancestor is a grass called teosinte, which still grows wild in parts of Mexico.

Teosinte has small spikes with only a handful of hard kernels, each locked inside a stony case. Nobody would think to grind it into meal. Yet scientists, using both genetic evidence and archaeology, have concluded that farmers in southern Mexico began growing teosinte thousands of years ago.

The change was slow and came through selection. Each season, farmers saved seeds from the plants with the biggest ears or the kernels that were easiest to remove, and they planted those. Over many generations, the plants changed. The ears grew larger, the kernels grew more numerous and more exposed, and the plant became one main stalk instead of many branches. In time, the plant could no longer scatter its own seeds. The kernels stayed tied to the cob, so corn now depends on people to plant it.

Farmers also kept breeding varieties for different climates and tastes, which is why corn comes in so many colors, including yellow, white, red, blue, and purple. Corn spread through the Americas and, after 1492, around the world.

Corn matters for what it gives, too. Its kernels can be ground into meal and flour, cooked fresh, or popped, and farmers also feed it to animals. Because modern fields often contain only a few varieties, scientists value the many older varieties and wild relatives as a store of useful traits that breeders may need in the future.

Questions

  1. What is the wild ancestor of corn? in the text

  2. Where does teosinte still grow wild? in the text

  3. How did farmers change the plant over time? in the text

  4. Why would nobody want to grind teosinte into meal? think about it

  5. Why does corn now depend on people to plant it? think about it

  6. Why does corn come in so many colors? in the text

Words to know

ancestor
an earlier type of plant or animal that later kinds came from
teosinte
a wild grass from which corn was bred
archaeology
the study of the past by digging up old objects and remains
selection
choosing certain plants or animals to breed
generations
groups of plants or animals born one after another
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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 · 259 words · Flesch-Kincaid grade 3.8

Corn, also called maize, feeds people and animals all over the world. But its wild ancestor looks nothing like the cobs in a store. The ancestor is a grass called teosinte. It still grows wild in parts of Mexico.

Teosinte has small spikes with just a few hard kernels. Each kernel sits in a stony case. No one would grind it into meal. Still, scientists have used genes and old digs to learn that farmers in southern Mexico began to grow teosinte thousands of years ago.

The change was slow. It came from selection. Each season, farmers saved seeds from plants with the biggest ears or kernels that were easy to remove. They planted those seeds. Over many generations, the plants changed. The ears grew bigger. The kernels grew more numerous and were not hidden. The plant grew one main stalk instead of many branches. In time, the plant could not scatter its own seeds. The kernels stay tied to the cob. So corn needs people to plant it.

Farmers also bred kinds of corn for different climates and tastes. That is why corn comes in yellow, white, red, blue, and purple. Corn spread through the Americas and, after 1492, around the world.

Corn matters for what it gives, too. Its kernels can be ground into meal and flour, cooked fresh, or popped. Farmers also feed it to animals. Modern fields often have only a few kinds of corn. So scientists value the many older kinds and wild cousins. They hold useful traits that breeders may need in the future.

▲ This passage · 269 words · Flesch-Kincaid grade 8.2

Corn, also called maize, feeds people and animals all over the world, yet its wild ancestor looks nothing like the cobs in a grocery store. The ancestor is a grass called teosinte, which still grows wild in parts of Mexico.

Teosinte has small spikes with only a handful of hard kernels, each locked inside a stony case. Nobody would think to grind it into meal. Yet scientists, using both genetic evidence and archaeology, have concluded that farmers in southern Mexico began growing teosinte thousands of years ago.

The change was slow and came through selection. Each season, farmers saved seeds from the plants with the biggest ears or the kernels that were easiest to remove, and they planted those. Over many generations, the plants changed. The ears grew larger, the kernels grew more numerous and more exposed, and the plant became one main stalk instead of many branches. In time, the plant could no longer scatter its own seeds. The kernels stayed tied to the cob, so corn now depends on people to plant it.

Farmers also kept breeding varieties for different climates and tastes, which is why corn comes in so many colors, including yellow, white, red, blue, and purple. Corn spread through the Americas and, after 1492, around the world.

Corn matters for what it gives, too. Its kernels can be ground into meal and flour, cooked fresh, or popped, and farmers also feed it to animals. Because modern fields often contain only a few varieties, scientists value the many older varieties and wild relatives as a store of useful traits that breeders may need in the future.

■ Harder · 290 words · Flesch-Kincaid grade 10

Corn, also known as maize, nourishes people and animals all over the world, yet its wild ancestor bears almost no resemblance to the cobs sold in a grocery store. The ancestor is a grass called teosinte, which still grows wild in certain parts of Mexico.

Teosinte produces small spikes with only a handful of hard kernels, each one locked inside a stony case. Hardly anyone would think of grinding it into meal. Nevertheless, scientists, drawing on both genetic evidence and archaeology, have concluded that farmers in southern Mexico began cultivating teosinte thousands of years ago.

The transformation was gradual and came about through selection. Each season, farmers saved seeds from the plants with the biggest ears or the kernels that were easiest to remove, and they planted those seeds the following year. Over many generations, the plants changed dramatically. The ears grew larger, the kernels became more numerous and more exposed, and the plant developed one main stalk instead of many branches. Eventually, the plant lost the ability to scatter its own seeds. The kernels remained tied to the cob, so corn now depends on people to plant it.

Farmers also continued to breed varieties suited to different climates and tastes, which explains why corn comes in such a wide range of colors, including yellow, white, red, blue, and purple. Corn spread throughout the Americas and, after 1492, around the entire world.

Corn matters for what it provides as well. Its kernels can be ground into meal and flour, cooked fresh, or popped, and farmers also feed it to animals. Because modern fields often contain only a few varieties, scientists value the many older varieties and wild relatives as a reservoir of useful traits that breeders may need in the future.

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 ancestor, teosinte, archaeology, selection and generations 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 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 "From Wild Grass to Corn on the Cob"?

It was written for 8th grade. It has 269 words and works out to a Flesch-Kincaid grade level of about 8.2. 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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