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Main Idea and Its Support is a free printable Grade 4 English worksheet on working out a main idea from the details that support it, aligned to Common Core standard RI.4.2. It prints 8 questions with an answer key on its own sheet of paper, in 25 versions that each ask different questions, so no two students in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 18 of 25 · the same problems every time you open this link.

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Set 1 has all 25 in a single PDF. All 25 sets ask different questions.

Main Idea and Its Support

RI.4.2

NameDate

Circle the right answer.

1.A paragraph says: Arctic foxes grow a thick white coat in winter; their small ears lose little heat; fur on their paws stops them slipping. What is its main idea?
  • A.Arctic foxes are suited to the cold.
  • B.Arctic foxes are white.
  • C.Ice is slippery.
2.A paragraph says: beavers fell trees with their teeth; they build dams of sticks and mud; their ponds give homes to fish and birds. What is its main idea?
  • A.Fish live in ponds.
  • B.Beavers change the places where they live.
  • C.Beavers have sharp teeth.
3.A paragraph says: some volcanoes pour out rivers of lava; others explode in clouds of ash; some have been quiet for thousands of years. What is its main idea?
  • A.Volcanoes behave in different ways.
  • B.Ash is gray.
  • C.Lava is hot.
4.A paragraph says: Fleming saw mold kill germs; Florey and Chain found a way to make it in large amounts; by 1944 it was treating soldiers. What is its main idea?
  • A.Making penicillin into a medicine took the work of many people.
  • B.Mold grows in dishes.
  • C.Soldiers were wounded in 1944.
5.A paragraph says: plastic bags take hundreds of years to break down; turtles mistake them for jellyfish; many towns now charge for bags. What is its main idea?
  • A.Plastic bags harm the natural world.
  • B.Turtles eat jellyfish.
  • C.Stores sell bags.
6.A paragraph says: earthworms tunnel through soil and let air in; they drag dead leaves underground; their waste makes the soil richer. What is its main idea?
  • A.Leaves fall in the fall.
  • B.Earthworms live underground.
  • C.Earthworms help keep soil healthy.
7.A paragraph says: Roman roads ran straight for miles; they were laid in layers so water drained away; some are still used today. What is its main idea?
  • A.Roman roads were built to last.
  • B.Water drains away.
  • C.Romans liked straight lines.
8.A paragraph says: trains ran to schedules across the country; each town had kept its own time; the railways needed one time everywhere. What is its main idea?
  • A.Towns had clocks.
  • B.The railways led to one time for the whole country.
  • C.Trains were often late.

LessonPrint · RI.4.2 · Set 18 · free to copy for classroom use

Answer key — Main Idea and Its Support

Set 18. Prints on its own sheet.

  1. 1.Arctic foxes are suited to the cold.
  2. 2.Beavers change the places where they live.
  3. 3.Volcanoes behave in different ways.
  4. 4.Making penicillin into a medicine took the work of many people.
  5. 5.Plastic bags harm the natural world.
  6. 6.Earthworms help keep soil healthy.
  7. 7.Roman roads were built to last.
  8. 8.The railways led to one time for the whole country.

More practice for RI.4.2

State the main idea, show the details behind it, and summarize.

Teaching this next? The Main Idea and a Summary is the 40-minute plan for it, with the misconceptions to expect.

All Grade 4 worksheets

Last reviewed 2026-09-05. Aligned to RI.4.2 of the Common Core State Standards for English Language Arts.