Main Idea and Key Details is a free printable Grade 3 English worksheet on matching a main idea to the key detail that supports it, aligned to Common Core standard RI.3.2. It prints 3 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 8 of 25 · the same problems every time you open this link.
Set 1 has all 25 in a single PDF. All 25 sets ask different questions.
Main Idea and Key Details
RI.3.2
NameDate
Write the letter of the detail next to each main idea.
1.Write the letter of the key detail that supports each main idea.
A salmon returns to the river where it hatched.
Beavers change rivers by building dams.
Morse code turns letters into short and long signals.
Bees work together to run the hive.
A.They pile up sticks and mud until the water backs up.
B.It finds the river by its smell.
C.E is one dot and T is one dash.
D.Some bees collect nectar while others guard the door.
2.Write the letter of the key detail that supports each main idea.
Cheese is made by separating the protein in milk.
Lighthouses keep ships away from rocks.
Frogs change shape as they grow.
Volcanoes form where melted rock escapes from the Earth.
A.Their lamps flash a pattern sailors can see at night.
B.Rennet splits the milk into curds and whey.
C.Lava pours out through a crack and cools into rock.
D.A tadpole grows back legs before front legs.
3.Write the letter of the key detail that supports each main idea.
A windmill turns moving air into turning stone.
Trees help keep soil in place.
Louis Braille invented a way for blind people to read.
Yeast makes bread rise.
A.It gives off gas that is trapped in the dough.
B.He used a cell of six raised dots.
C.Their roots hold the earth together in heavy rain.
D.The sails turn a shaft that turns the millstone.
LessonPrint · RI.3.2 · Set 8 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 8. Prints on its own sheet.
1.1. A salmon returns to the river where it hatched. — B (It finds the river by its smell.) 2. Beavers change rivers by building dams. — A (They pile up sticks and mud until the water backs up.) 3. Morse code turns letters into short and long signals. — C (E is one dot and T is one dash.) 4. Bees work together to run the hive. — D (Some bees collect nectar while others guard the door.)
2.1. Cheese is made by separating the protein in milk. — B (Rennet splits the milk into curds and whey.) 2. Lighthouses keep ships away from rocks. — A (Their lamps flash a pattern sailors can see at night.) 3. Frogs change shape as they grow. — D (A tadpole grows back legs before front legs.) 4. Volcanoes form where melted rock escapes from the Earth. — C (Lava pours out through a crack and cools into rock.)
3.1. A windmill turns moving air into turning stone. — D (The sails turn a shaft that turns the millstone.) 2. Trees help keep soil in place. — C (Their roots hold the earth together in heavy rain.) 3. Louis Braille invented a way for blind people to read. — B (He used a cell of six raised dots.) 4. Yeast makes bread rise. — A (It gives off gas that is trapped in the dough.)
More practice for RI.3.2
State the main idea and show which details hold it up.