Reading nonfiction: main idea and key details (grade 3) · lesson

The main idea

💡 The main idea is what most of the text is about, not just one small part.

The topic is what a text is about in a word or two, like frogs. The main idea says the big point about the topic.

To find it, ask what most of the parts tell about. One fun fact is a detail, not the main idea.

The title and the first sentence often give a hint.

🧠 Let's work it out

A text about a town fair has three parts. One tells about the rides. One tells about the food. One tells about the pie contest.

Ask: what do all three parts tell?
Fun things to do at the fair.
So the main idea is that the fair has something fun for everyone.
The pie contest alone is a detail.

What do you think comes next?

topic: what a text is about, in a word or two
main idea: the big point most of the text tells

Look back for key details

💡 When a question asks for a fact, go back and find the sentence that says it.

Key details are facts that help you understand a text. They can be names, numbers, places, or what something is called.

Do not answer from memory. Find a word from the question in the text. Read that part.

Be careful with numbers. A text may tell what is true now and what someone wants. Pick the one the question asks.

🧠 Let's work it out

Question: What does a baby kangaroo live in?

Find the word baby in the text.
It says, A baby kangaroo lives in a pouch.
So the answer is a pouch.

What do you think comes next?

fact: something that is true and can be checked
key detail: a fact that helps explain the main idea

How and why things happen

💡 Facts in a science text often explain why something happens or how it is done step by step.

Some texts explain why. Look for the word because, or for a fact that comes right before the result.

Some texts tell steps. Look for first, next, then, and last. Each step needs the one before it.

To answer a why question, find the thing that happens. Then look for the reason right next to it.

🧠 Let's work it out

Text: A cactus stores water in its thick stem. This helps it live where it seldom rains. Question: Why does a cactus have a thick stem?

Find the thick stem.
The next words tell what it does: it stores water.
So the reason is to hold water for dry times.

What do you think comes next?

reason: why something happens
step: one part of a job done in order

Opinion and reasons

💡 An opinion piece tells what the author thinks and gives reasons to back it up.

Some nonfiction tries to get you to agree. The author's opinion is the big thing they want. It is often in the first sentence. Look for I think or should.

Then the author gives reasons. Words like first, second, and also often start each reason.

A reason is not just any fact. It tells why the opinion is a good idea. Some sentences back up one reason. To find them, pick the ones about that reason, not about a different one.

🧠 Let's work it out

Text: I think our town needs a dog park. First, dogs need room to run. Second, owners can meet new friends.

Ask: what does the author want? A dog park.
That is the opinion.
Why? Dogs need room, and owners make friends.
Those are the reasons.

What do you think comes next?

opinion: what someone thinks or believes
reason: why the author thinks the opinion is right