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 20 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.
Swallows leave Britain to follow their food.
Bees work together to run the hive.
Morse code turns letters into short and long signals.
A canal lock lets boats climb hills.
A.Flying insects disappear in October.
B.E is one dot and T is one dash.
C.Water flows in and the boat rises with it.
D.Some bees collect nectar while others guard the door.
2.Write the letter of the key detail that supports each main idea.
Trees help keep soil in place.
Beavers change rivers by building dams.
A windmill turns moving air into turning stone.
Frogs change shape as they grow.
A.They pile up sticks and mud until the water backs up.
B.A tadpole grows back legs before front legs.
C.The sails turn a shaft that turns the millstone.
D.Their roots hold the earth together in heavy rain.
3.Write the letter of the key detail that supports each main idea.
Lighthouses keep ships away from rocks.
Volcanoes form where melted rock escapes from the Earth.
Cheese is made by separating the protein in milk.
Yeast makes bread rise.
A.Rennet splits the milk into curds and whey.
B.Lava pours out through a crack and cools into rock.
C.It gives off gas that is trapped in the dough.
D.Their lamps flash a pattern sailors can see at night.
LessonPrint · RI.3.2 · Set 20 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 20. Prints on its own sheet.
1.1. Swallows leave Britain to follow their food. — A (Flying insects disappear in October.) 2. Bees work together to run the hive. — D (Some bees collect nectar while others guard the door.) 3. Morse code turns letters into short and long signals. — B (E is one dot and T is one dash.) 4. A canal lock lets boats climb hills. — C (Water flows in and the boat rises with it.)
2.1. Trees help keep soil in place. — D (Their roots hold the earth together in heavy rain.) 2. Beavers change rivers by building dams. — A (They pile up sticks and mud until the water backs up.) 3. A windmill turns moving air into turning stone. — C (The sails turn a shaft that turns the millstone.) 4. Frogs change shape as they grow. — B (A tadpole grows back legs before front legs.)
3.1. Lighthouses keep ships away from rocks. — D (Their lamps flash a pattern sailors can see at night.) 2. Volcanoes form where melted rock escapes from the Earth. — B (Lava pours out through a crack and cools into rock.) 3. Cheese is made by separating the protein in milk. — A (Rennet splits the milk into curds and whey.) 4. Yeast makes bread rise. — C (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.