Reading nonfiction: central idea, evidence, and development (grade 9) · lesson

Central idea

💡 The central idea is the main point the whole text builds toward, not one interesting fact inside it.

A central idea covers the whole text. Test a choice by asking, "Does every paragraph help explain or support this?" If only one paragraph does, it's a detail.

Look at the title, the opening, and the ending. Writers often set up a problem early and solve it or sum it up at the end.

Choices that are too broad claim more than the text says. Choices that are too narrow cover just one part.

🧠 Let's work it out

An article covers how the Romans built roads, why the roads lasted, and how some are still used.

"Roman roads were made of stone" is one detail.
"The Romans liked to travel" is too broad and vague.
"Roman roads were built so well that some still work today" covers all three parts.

What do you think comes next?

central idea: the main point of a whole text

Finding stated details

💡 When a question says "according to the passage," the answer is stated in the text, so find the sentence and match it.

"According to the passage" means the text states the answer. Skim for key words from the question, then read the sentences around them.

Wrong choices often reuse real words from the text but twist them. Others state something true that the passage never says.

For a typed answer, give just what the question asks for. If it says "type a number," type only the number.

🧠 Let's work it out

Question: according to the article, why did the dam need repairs?

Skim for "repair."
The text says, "Cracks formed after years of freezing and thawing."
So the answer is cracks from freezing and thawing.
The dam's age might be mentioned too, but it's not the reason unless the text links it to the repairs.

What do you think comes next?

🔗 Khan Academy: Key ideas and details, long passages (grade 9) · Khan Academy (free) ↗

Claims and reasons

💡 An argument's claim is the position the writer wants you to accept, and reasons are the main "because" statements behind it.

The claim is what the writer argues for. It's often stated near the start and repeated at the end. Phrases like "I believe" or "should" often flag it. It's an opinion others could disagree with.

Reasons answer the question "Why should I agree?" Each reason usually gets its own paragraph. Writers often signal them with words like "first," "also," and "finally."

Don't mix up the claim with a detail, or with a fix the writer offers for the other side's worry. Ask: what is the one thing the writer wants to happen or wants me to believe?

🧠 Let's work it out

A letter says: "Our school should start at nine. First, teens need more sleep. Second, fewer students would be late. Some say buses can't change, but the district could shift routes."

The claim: start school at nine.
The reasons: sleep and lateness.
The bus idea is a reply to a worry, not a main reason.

What do you think comes next?

claim: the main point an argument tries to prove
reason: a "because" statement that supports a claim

Evidence that supports a point

💡 Evidence supports a point only if it shows that exact point is true, and the best evidence is concrete, like counts, studies, or direct observations.

Evidence is the proof under a reason: numbers, examples, studies, or what someone saw. Match evidence to the exact reason it backs up. A fact about cost supports a money reason, not a safety reason. A strong-looking number can still fit the wrong reason, so check the match first.

Some evidence is stronger than others. A count of real events beats a vague feeling. Ask: does this detail show the point, or does it just repeat it?

Check numbers with care. If a question asks what a number shows, compare the part to the whole. A small part can't explain most of a large total.

🧠 Let's work it out

A writer says the park needs more benches because older visitors have nowhere to rest. Which evidence fits best?

"In the park's survey, 40 of 50 older visitors said they skip the long trail because there is nowhere to rest" shows the need directly.
"Benches come in many colors" is off topic.
Pick the detail that proves that exact reason.

What do you think comes next?

evidence: facts, examples, or data that support a point

How ideas develop

💡 Informational texts build ideas in an order, through time, through steps, or by adding a test or result to what came before.

Writers develop an idea step by step. A paragraph might add a new detail, explain how something works, or show what happened next. Ask what each paragraph adds to the one before it.

Many texts move through time. Dates and words like "later," "by then," and "today" help you track the order. Verb tense is a clue too: past-tense verbs point back, and words like "now" mark the present.

A final paragraph often extends the idea. It may add a test, a result, or one more step that completes the explanation.

🧠 Let's work it out

An article explains how a rainbow forms.

Paragraph one: sunlight holds every color.
Paragraph two: raindrops bend the light.
Paragraph three: each color bends a different amount, so the colors spread into bands.
Each paragraph adds a step, and the last explains the shape you see.
To put ideas in order, follow the time words or the steps.

What do you think comes next?