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 1 of 25 · the same problems every time you open this link.
Write the letter of the detail next to each main idea.
1.Write the letter of the key detail that supports each main idea.
Volcanoes form where melted rock escapes from the Earth.
Lighthouses keep ships away from rocks.
Bees work together to run the hive.
Yeast makes bread rise.
A.Some bees collect nectar while others guard the door.
B.Their lamps flash a pattern sailors can see at night.
C.It gives off gas that is trapped in the dough.
D.Lava pours out through a crack and cools into rock.
2.Write the letter of the key detail that supports each main idea.
A canal lock lets boats climb hills.
Swallows leave Britain to follow their food.
Frogs change shape as they grow.
Beavers change rivers by building dams.
A.A tadpole grows back legs before front legs.
B.They pile up sticks and mud until the water backs up.
C.Flying insects disappear in October.
D.Water flows in and the boat rises with it.
3.Write the letter of the key detail that supports each main idea.
Morse code turns letters into short and long signals.
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.He used a cell of six raised dots.
B.Rennet splits the milk into curds and whey.
C.E is one dot and T is one dash.
D.Their roots hold the earth together in heavy rain.
LessonPrint · RI.3.2 · Set 1 · free to copy for classroom use
Answer key — Main Idea and Key Details
Set 1. Prints on its own sheet.
1.1. Volcanoes form where melted rock escapes from the Earth. — D (Lava pours out through a crack and cools into rock.) 2. Lighthouses keep ships away from rocks. — B (Their lamps flash a pattern sailors can see at night.) 3. Bees work together to run the hive. — A (Some bees collect nectar while others guard the door.) 4. Yeast makes bread rise. — C (It gives off gas that is trapped in the dough.)
2.1. A canal lock lets boats climb hills. — D (Water flows in and the boat rises with it.) 2. Swallows leave Britain to follow their food. — C (Flying insects disappear in October.) 3. Frogs change shape as they grow. — A (A tadpole grows back legs before front legs.) 4. Beavers change rivers by building dams. — B (They pile up sticks and mud until the water backs up.)
3.1. Morse code turns letters into short and long signals. — C (E is one dot and T is one dash.) 2. Trees help keep soil in place. — D (Their roots hold the earth together in heavy rain.) 3. Louis Braille invented a way for blind people to read. — A (He used a cell of six raised dots.) 4. Cheese is made by separating the protein in milk. — B (Rennet splits the milk into curds and whey.)
Questions about Main Idea and Key Details
What does the Main Idea and Key Details worksheet cover?
It practices matching a main idea to the key detail that supports it — 3 questions for Grade 3, all on Common Core RI.3.2: State the main idea and show which details hold it up. The instruction to students is “Write the letter of the detail next to each main idea”, and the answer key follows on the next sheet.
Which Common Core standard does Main Idea and Key Details practice?
CCSS.ELA-LITERACY.RI.3.2 — RI.3.2, under Reading: Informational Text for Grade 3. The published standard reads: “Determine the main idea of a text; recount the key details and explain how they support the main idea.” The worksheet assesses that standard rather than a paraphrase of it.
What age or grade is this worksheet for?
Main Idea and Key Details is written for Grade 3, typically ages 8-9. It is one of the sheets on RI.3.2, so it suits any student working at that standard — including older students revisiting it and younger ones working ahead.
Does Main Idea and Key Details come with an answer key?
Yes. All 3 answers are generated from the same problems as the questions, so the key cannot drift out of step with the sheet. It starts on a fresh sheet of paper, after the questions, so it is not handed out with the class by accident.
How many different versions of Main Idea and Key Details can I print?
25 — one per student, and all 25 ask different questions. Set 1 downloads the whole class as a single PDF. Every version is fixed to its own address, so a sheet printed today holds the same problems when you reopen it next week.
Is Main Idea and Key Details free to print and photocopy?
Yes. Main Idea and Key Details, its answer key and its 25 versions are free to print and photocopy for your own class, with no account, no email capture and no subscription at the download step. Please do not resell them or republish them as your own.
Is there a lesson plan to teach RI.3.2?
Yes — “Main Idea and Supporting Details” is a 40-minute Grade 3 plan for RI.3.2, timed section by section, with the misconceptions to expect and an exit ticket. Main Idea and Key Details is the practice that follows it.
More practice for RI.3.2
State the main idea and show which details hold it up.