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 3 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 salmon returns to the river where it hatched.
Morse code turns letters into short and long signals.
Swallows leave Britain to follow their food.
Bees work together to run the hive.
A.Some bees collect nectar while others guard the door.
B.E is one dot and T is one dash.
C.Flying insects disappear in October.
D.It finds the river by its smell.
2.Write the letter of the key detail that supports each main idea.
Trees help keep soil in place.
Louis Braille invented a way for blind people to read.
Cheese is made by separating the protein in milk.
A windmill turns moving air into turning stone.
A.He used a cell of six raised dots.
B.The sails turn a shaft that turns the millstone.
C.Their roots hold the earth together in heavy rain.
D.Rennet splits the milk into curds and whey.
3.Write the letter of the key detail that supports each main idea.
Lighthouses keep ships away from rocks.
A canal lock lets boats climb hills.
Yeast makes bread rise.
Beavers change rivers by building dams.
A.Their lamps flash a pattern sailors can see at night.
B.Water flows in and the boat rises with it.
C.They pile up sticks and mud until the water backs up.
D.It gives off gas that is trapped in the dough.
LessonPrint · RI.3.2 · Set 3 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 3. Prints on its own sheet.
1.1. A salmon returns to the river where it hatched. — D (It finds the river by its smell.) 2. Morse code turns letters into short and long signals. — B (E is one dot and T is one dash.) 3. Swallows leave Britain to follow their food. — C (Flying insects disappear in October.) 4. Bees work together to run the hive. — A (Some bees collect nectar while others guard the door.)
2.1. Trees help keep soil in place. — C (Their roots hold the earth together in heavy rain.) 2. Louis Braille invented a way for blind people to read. — A (He used a cell of six raised dots.) 3. Cheese is made by separating the protein in milk. — D (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.)
3.1. Lighthouses keep ships away from rocks. — A (Their lamps flash a pattern sailors can see at night.) 2. A canal lock lets boats climb hills. — B (Water flows in and the boat rises with it.) 3. Yeast makes bread rise. — D (It gives off gas that is trapped in the dough.) 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.