Reading nonfiction: central idea and key details (grade 8) · lesson

The central idea

💡 A strong central idea statement sums up the whole passage: the problem, what happened, and what it led to.

The central idea is the main point of the whole text. In history and science passages, it often joins a cause, an event, and an effect.

Wrong choices are usually true details. They cover only one paragraph.

Ask which statement every paragraph helps explain.

🧠 Let's work it out

Passage: a city's water was unsafe (paragraph 1).

A doctor traced sickness to one well (paragraph 2).
The city built clean pipes (paragraph 3).
"A doctor's work found the cause of sickness and led to clean water" covers all three.

What do you think comes next?

central idea: the main point of a whole text

🔗 Khan Academy: Key ideas and details, longer passages (grade 8) · Khan Academy ↗

Pulling out exact details

💡 When the answer is a fact from the passage, find the sentence that states it and match it exactly.

For "according to the passage" questions, search for the key word from the question.

Some questions ask you to type a word from the passage. Copy the word as it is spelled there.

For two-part answers, find two details that are each stated in the text.

🧠 How to think about it

Question: what did sailors call the tool that measured speed? Passage: "Sailors used a knotted rope called a log line." Find "called": the answer is "log line." Type the words from the passage.

key word: an important word from the question to search for

Explaining causes

💡 To explain why something happened, connect the cause to its effect using the passage's own reasons.

Many nonfiction passages show a chain: one change leads to another. To explain a "why" question, find the link.

Look for cause words like "because," "so," and "as a result." The cause and effect are often in the same sentence or the next one.

🧠 Let's work it out

Passage: "Before trains, fresh fish could not reach towns far from the sea. With fast trains, fish arrived before it spoiled." Why couldn't inland towns get fresh fish?

The trip was too slow, and the fish spoiled.
Trains fixed the cause.

What do you think comes next?

effect: what happens because of a cause

Claims, reasons, and calls to action

💡 Trace an argument by finding the claim, each reason, and what the author asks readers to do.

The claim is the author's main position. It is often at the end of the first paragraph and again in the conclusion.

Reasons explain why the claim is right. Each reason may have its own example.

A call to action tells readers or leaders what to do next. It often ends the argument.

🧠 Let's work it out

Essay: "Schools should add music class. Music builds memory. It also teaches teamwork. Principals should hire a music teacher next fall."

Claim: add music class.
Reasons: memory, teamwork.
Call to action: hire a teacher next fall.

What do you think comes next?

claim: the author's main position
call to action: what the author asks readers to do