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 15 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 canal lock lets boats climb hills.
A salmon returns to the river where it hatched.
Cheese is made by separating the protein in milk.
A windmill turns moving air into turning stone.
A.Rennet splits the milk into curds and whey.
B.The sails turn a shaft that turns the millstone.
C.Water flows in and the boat rises with it.
D.It finds the river by its smell.
2.Write the letter of the key detail that supports each main idea.
Swallows leave Britain to follow their food.
Yeast makes bread rise.
Trees help keep soil in place.
Volcanoes form where melted rock escapes from the Earth.
A.Flying insects disappear in October.
B.Their roots hold the earth together in heavy rain.
C.Lava pours out through a crack and cools into rock.
D.It gives off gas that is trapped in the dough.
3.Write the letter of the key detail that supports each main idea.
Morse code turns letters into short and long signals.
Frogs change shape as they grow.
Lighthouses keep ships away from rocks.
Beavers change rivers by building dams.
A.Their lamps flash a pattern sailors can see at night.
B.They pile up sticks and mud until the water backs up.
C.A tadpole grows back legs before front legs.
D.E is one dot and T is one dash.
LessonPrint · RI.3.2 · Set 15 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 15. Prints on its own sheet.
1.1. A canal lock lets boats climb hills. — C (Water flows in and the boat rises with it.) 2. A salmon returns to the river where it hatched. — D (It finds the river by its smell.) 3. Cheese is made by separating the protein in milk. — A (Rennet splits the milk into curds and whey.) 4. A windmill turns moving air into turning stone. — B (The sails turn a shaft that turns the millstone.)
2.1. Swallows leave Britain to follow their food. — A (Flying insects disappear in October.) 2. Yeast makes bread rise. — D (It gives off gas that is trapped in the dough.) 3. Trees help keep soil in place. — B (Their roots hold the earth together in heavy rain.) 4. Volcanoes form where melted rock escapes from the Earth. — C (Lava pours out through a crack and cools into rock.)
3.1. Morse code turns letters into short and long signals. — D (E is one dot and T is one dash.) 2. Frogs change shape as they grow. — C (A tadpole grows back legs before front legs.) 3. Lighthouses keep ships away from rocks. — A (Their lamps flash a pattern sailors can see at night.) 4. Beavers change rivers by building dams. — B (They pile up sticks and mud until the water backs up.)
More practice for RI.3.2
State the main idea and show which details hold it up.