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 17 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.
Cheese is made by separating the protein in milk.
Morse code turns letters into short and long signals.
Lighthouses keep ships away from rocks.
Yeast makes bread rise.
A.It gives off gas that is trapped in the dough.
B.Their lamps flash a pattern sailors can see at night.
C.E is one dot and T is one dash.
D.Rennet splits the milk into curds and whey.
2.Write the letter of the key detail that supports each main idea.
Louis Braille invented a way for blind people to read.
Frogs change shape as they grow.
Volcanoes form where melted rock escapes from the Earth.
A salmon returns to the river where it hatched.
A.He used a cell of six raised dots.
B.Lava pours out through a crack and cools into rock.
C.It finds the river by its smell.
D.A tadpole grows back legs before front legs.
3.Write the letter of the key detail that supports each main idea.
Trees help keep soil in place.
A canal lock lets boats climb hills.
Swallows leave Britain to follow their food.
Beavers change rivers by building dams.
A.Water flows in and the boat rises with it.
B.Their roots hold the earth together in heavy rain.
C.They pile up sticks and mud until the water backs up.
D.Flying insects disappear in October.
LessonPrint · RI.3.2 · Set 17 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 17. Prints on its own sheet.
1.1. Cheese is made by separating the protein in milk. — D (Rennet splits the milk into curds and whey.) 2. Morse code turns letters into short and long signals. — C (E is one dot and T is one dash.) 3. Lighthouses keep ships away from rocks. — B (Their lamps flash a pattern sailors can see at night.) 4. Yeast makes bread rise. — A (It gives off gas that is trapped in the dough.)
2.1. Louis Braille invented a way for blind people to read. — A (He used a cell of six raised dots.) 2. Frogs change shape as they grow. — D (A tadpole grows back legs before front legs.) 3. Volcanoes form where melted rock escapes from the Earth. — B (Lava pours out through a crack and cools into rock.) 4. A salmon returns to the river where it hatched. — C (It finds the river by its smell.)
3.1. Trees help keep soil in place. — B (Their roots hold the earth together in heavy rain.) 2. A canal lock lets boats climb hills. — A (Water flows in and the boat rises with it.) 3. Swallows leave Britain to follow their food. — D (Flying insects disappear in October.) 4. Beavers change rivers by building dams. — C (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.