Skip to content
LessonPrint

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

Next setLesson plan

One paper per student

12345678910111213141516171819202122232425

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.Soldiers were wounded in 1944.
  • B.Mold grows in dishes.
  • C.Making penicillin into a medicine took the work of many people.
2.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.Rocks are dangerous.
  • B.Lighthouses keep ships safe and help them find their way.
  • C.Lights can flash.
3.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.Fish lay eggs.
  • B.Coral reefs are very small.
  • C.Coral reefs are home to a great deal of sea life.
4.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.Earthworms live underground.
  • C.Leaves fall in the fall.
5.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.Fish live in ponds.
  • C.Beavers change the places where they live.
6.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.Romans liked straight lines.
  • C.Roman roads were built to last.
7.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.
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.The railways led to one time for the whole country.
  • B.Towns had clocks.
  • C.Trains were often late.

LessonPrint · RI.4.2 · Set 22 · free to copy for classroom use

Answer key — Main Idea and Its Support

Set 22. Prints on its own sheet.

  1. 1.Making penicillin into a medicine took the work of many people.
  2. 2.Lighthouses keep ships safe and help them find their way.
  3. 3.Coral reefs are home to a great deal of sea life.
  4. 4.Earthworms help keep soil healthy.
  5. 5.Beavers change the places where they live.
  6. 6.Roman roads were built to last.
  7. 7.Telephones have changed a great deal over time.
  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.