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