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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 16 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: 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.Beavers change the places where they live.
  • B.Fish live in ponds.
  • C.Beavers have sharp teeth.
2.A paragraph says: honeybees carry pollen from flower to flower; without them many fruits would not grow; farmers rent hives for their orchards. What is its main idea?
  • A.Farmers keep hives.
  • B.Bees are important for growing food.
  • C.Flowers have pollen.
3.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.
4.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.Stores sell bags.
  • B.Turtles eat jellyfish.
  • C.Plastic bags harm the natural world.
5.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.
6.A paragraph says: libraries lend books for free; many offer computers anyone can use; they run reading clubs for children. What is its main idea?
  • A.Computers are useful.
  • B.Libraries offer many free services to a town.
  • C.Children like clubs.
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.Water drains away.
  • B.Roman roads were built to last.
  • C.Romans liked straight lines.
8.A paragraph says: coral reefs cover a tiny part of the sea floor; a quarter of all sea creatures live on them; many fish lay their eggs there. What is its main idea?
  • A.Coral reefs are very small.
  • B.Coral reefs are home to a great deal of sea life.
  • C.Fish lay eggs.

LessonPrint · RI.4.2 · Set 16 · free to copy for classroom use

Answer key — Main Idea and Its Support

Set 16. Prints on its own sheet.

  1. 1.Beavers change the places where they live.
  2. 2.Bees are important for growing food.
  3. 3.Earthworms help keep soil healthy.
  4. 4.Plastic bags harm the natural world.
  5. 5.Making penicillin into a medicine took the work of many people.
  6. 6.Libraries offer many free services to a town.
  7. 7.Roman roads were built to last.
  8. 8.Coral reefs are home to a great deal of sea life.

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.