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 19 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.
Cheese is made by separating the protein in milk.
Trees help keep soil in place.
Lighthouses keep ships away from rocks.
A.Rennet splits the milk into curds and whey.
B.Their roots hold the earth together in heavy rain.
C.Their lamps flash a pattern sailors can see at night.
D.Water flows in and the boat rises with it.
2.Write the letter of the key detail that supports each main idea.
Volcanoes form where melted rock escapes from the Earth.
A salmon returns to the river where it hatched.
Morse code turns letters into short and long signals.
A windmill turns moving air into turning stone.
A.It finds the river by its smell.
B.E is one dot and T is one dash.
C.Lava pours out through a crack and cools into rock.
D.The sails turn a shaft that turns the millstone.
3.Write the letter of the key detail that supports each main idea.
Bees work together to run the hive.
Frogs change shape as they grow.
Louis Braille invented a way for blind people to read.
Swallows leave Britain to follow their food.
A.A tadpole grows back legs before front legs.
B.He used a cell of six raised dots.
C.Flying insects disappear in October.
D.Some bees collect nectar while others guard the door.
LessonPrint · RI.3.2 · Set 19 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 19. Prints on its own sheet.
1.1. A canal lock lets boats climb hills. — D (Water flows in and the boat rises with it.) 2. Cheese is made by separating the protein in milk. — A (Rennet splits the milk into curds and whey.) 3. Trees help keep soil in place. — B (Their roots hold the earth together in heavy rain.) 4. Lighthouses keep ships away from rocks. — C (Their lamps flash a pattern sailors can see at night.)
2.1. Volcanoes form where melted rock escapes from the Earth. — C (Lava pours out through a crack and cools into rock.) 2. A salmon returns to the river where it hatched. — A (It finds the river by its smell.) 3. Morse code turns letters into short and long signals. — B (E is one dot and T is one dash.) 4. A windmill turns moving air into turning stone. — D (The sails turn a shaft that turns the millstone.)
3.1. Bees work together to run the hive. — D (Some bees collect nectar while others guard the door.) 2. Frogs change shape as they grow. — A (A tadpole grows back legs before front legs.) 3. Louis Braille invented a way for blind people to read. — B (He used a cell of six raised dots.) 4. Swallows leave Britain to follow their food. — C (Flying insects disappear in October.)
More practice for RI.3.2
State the main idea and show which details hold it up.