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Common Core ELAGrades 9–10Reading: Informational

RI.9-10.2: Central Idea and Objective Summary

Also written as CCSS.ELA-LITERACY.RI.9-10.2 · Cluster: Key Ideas and Details.

All 41 Grades 9–10 ELA Standards

The Official Wording

Determine a central idea of a text and analyze its development over the course of the text, including how it emerges and is shaped and refined by specific details; provide an objective summary of the text.

Common Core State Standards, Grades 9-10, Reading: Informational Text · Read it at the source · Checked October 14, 2026

What RI.9-10.2 Means in Plain English

Ninth and tenth graders find a text’s central idea and trace it: where it first surfaces and which facts and examples sharpen it along the way. A history of penicillin may open on one scientist while its central idea belongs to the many people who followed.

Eighth grade (RI.8.2) related a central idea to its supporting ideas. Ninth and tenth grade follow how details shape and refine it over the whole text, and the summary must stay free of opinion. Eleventh and twelfth grade (RI.11-12.2) track two or more central ideas as they interact.

RI.9-10.2 I Can Statements

  • I can state a central idea that fits the whole text.
  • I can show how specific details sharpen the central idea.
  • I can write a summary with no opinions in it.

RI.9-10.2 Worked Example

The passage opens on a famous discovery, but most of it is about what came after, and the weak answer stops at the opening.

Read the Story
In 1928, Alexander Fleming noticed that a stray mold had killed the bacteria around it in one of his lab dishes. He named the substance it made penicillin, but he could not purify it, and for about a decade it was little more than a curiosity.Around 1940, a team at Oxford led by Howard Florey and Ernst Chain found a way to extract and purify it. Mice infected with deadly bacteria survived when they were treated.The first person they treated, a police officer with a raging infection, began to recover in 1941. Then the supply ran out. The team even recovered penicillin from his urine to give it to him again, but he died.With Britain at war, the work moved to the United States. At a government lab in Peoria, Illinois, researchers grew the mold in vats fed with corn steep liquor, a cheap leftover of corn processing, and in 1943 a moldy cantaloupe from a local market turned out to carry a strain that, once improved, made many times more penicillin than Fleming’s.By D-Day in June 1944, American companies had produced some 2.3 million doses for the invasion of Normandy.
A short passage written for this page.
Question: What is the central idea of the passage, and how do specific details sharpen it as the passage goes on? Then write a two-sentence objective summary.
Not Yet“The central idea is that Alexander Fleming discovered penicillin by accident and saved millions of lives. It shows how amazing he was. Summary: Fleming was a genius who found a mold that cured infections.”It takes the opening detail for the whole idea, though four of the five paragraphs are about other people. The summary slips in opinion with “amazing” and “genius,” and it credits Fleming with a cure the passage says he could not make.
Meets the Standard“The central idea is that penicillin became a medicine only after years of work by many people to purify it and make enough of it. The idea first appears in the opening paragraph, where Fleming finds the mold but ‘could not purify it.’ The Oxford team purifies it, but the officer who began to recover died when ‘the supply ran out,’ which shifts the problem from discovery to quantity. The Peoria vats and the cantaloupe strain solve that problem, and the 2.3 million doses show it solved. Summary: Fleming found penicillin in 1928 but could not purify it. An Oxford team purified it around 1940, and American labs learned to mass-produce it in time for the 1944 invasion of Normandy.”It states the idea in its own words, shows where it first appears and how each later detail narrows it from discovery to supply, and keeps every judgment out of the summary.
Question Stems to Use
What idea do all the paragraphs serve, not just the first one?Where does the idea first appear? Which detail plants it?Which detail changes or narrows the idea? How?What would a reader miss about the idea if this paragraph were cut?Does your summary contain any word that shows your opinion? Cut it.

Common Mistakes with RI.9-10.2

Mistaking the opening story for the central idea

“The text is about how Fleming discovered penicillin.”

Try this: Have students check a proposed central idea against every paragraph and revise it until each paragraph clearly serves it.

Listing details instead of tracing development

Fleming, then Oxford, then Peoria, then D-Day, with no word on what each adds to the idea

Try this: Ask for one sentence per section naming how it changes the idea: plants it, complicates it, narrows it or settles it.

Letting opinion into the summary

“Fleming was a genius who saved the world.”

Try this: Have students underline every judgment word in their summary, such as amazing, genius or sadly, and rewrite those sentences as plain facts.

Where RI.9-10.2 Fits

Comes BeforeRI.8.2Analyze a central idea’s development, including its relationship to supporting ideas, and summarize objectively.
AlongsideRL.9-10.2Trace how a theme emerges and is refined in a novel or play, with an objective summary.RH.9-10.2Find the central ideas of a primary or secondary source and summarize how events develop.
Comes NextRI.11-12.2Analyze how two or more central ideas interact and build on one another.

Practice RI.9-10.2

Quick Check

  1. What is the central idea of the passage?
  2. Which detail shifts the problem from discovering penicillin to producing enough of it?
  3. Why does “Fleming was a genius” not belong in an objective summary?

RI.9-10.2: Other Names

RI.9-10.2CCSS.ELA-LITERACY.RI.9-10.2

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.