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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 25 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: 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.Soldiers were wounded in 1944.
  • C.Mold grows in dishes.
2.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.Earthworms help keep soil healthy.
  • B.Leaves fall in the fall.
  • C.Earthworms live underground.
3.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.Trains were often late.
  • C.The railways led to one time for the whole country.
4.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 have sharp teeth.
  • B.Beavers change the places where they live.
  • C.Fish live in ponds.
5.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.Ice is slippery.
  • B.Arctic foxes are white.
  • C.Arctic foxes are suited to the cold.
6.A paragraph says: lighthouses warn ships away from rocks; each one flashes its own pattern; sailors use the pattern to tell where they are. What is its main idea?
  • A.Lights can flash.
  • B.Rocks are dangerous.
  • C.Lighthouses keep ships safe and help them find their way.
7.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.Children like clubs.
  • C.Libraries offer many free services to a town.
8.A paragraph says: early phones were fixed to the wall; later phones had no cord; today's phones fit in a pocket and take photos. What is its main idea?
  • A.Telephones have changed a great deal over time.
  • B.Walls hold phones.
  • C.Phones take photos.

LessonPrint · RI.4.2 · Set 25 · free to copy for classroom use

Answer key — Main Idea and Its Support

Set 25. Prints on its own sheet.

  1. 1.Making penicillin into a medicine took the work of many people.
  2. 2.Earthworms help keep soil healthy.
  3. 3.The railways led to one time for the whole country.
  4. 4.Beavers change the places where they live.
  5. 5.Arctic foxes are suited to the cold.
  6. 6.Lighthouses keep ships safe and help them find their way.
  7. 7.Libraries offer many free services to a town.
  8. 8.Telephones have changed a great deal over time.

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.