Determine the main ideas of an article, explain how key details support them, and summarize it with the other important information

Learning goal: This lesson teaches the two parts of Ohio's 2026 standard RI.5.2, first implemented in 2027-28, which asks you to analyze the development of ideas in an informational text. You will determine the main idea or main ideas of a text and explain how they are supported by key details (RI.5.2a), and you will summarize an informational text, including its main ideas and key details as well as other important information (RI.5.2b).

Topic, main idea and detail. These three words name different things. The topic is what the text is about, usually a word or a short phrase: compost. The main idea is the most important point the author makes about the topic, in a section or in the whole text. A main idea is a complete sentence: "A school compost project works only when everyone sorts scraps carefully." A key detail is a fact, example, number, step or reason that supports or explains a main idea. Key details are the proof; the main idea is the point they prove.

How to determine a main idea. Use four steps.

1. Name the topic in a word or phrase.
2. For each paragraph, write a short note that says what the paragraph tells about the topic.
3. Look across the notes for the point that most of them support. Headings, first sentences and last sentences are useful clues, but test them; the first sentence of a paragraph is sometimes an attention grabber, not the main idea.
4. State the main idea as your own complete sentence that covers the notes without going beyond them.

Two conditions keep a main idea accurate. It must not be too narrow: "Students found plastic forks in the bins" is one detail, not the point of the paragraph. It must not be too broad: "Every school should compost" says more than the article claims. A good main idea is as wide as its details and no wider. Many authors never state the main idea in one sentence; then you build it yourself from the notes.

More than one main idea. A longer informational text often develops two or more main ideas, each with its own group of key details. Signs that a new main idea has begun include a new heading, a new question, a shift from explaining how something works to telling what happened, or a section about a problem and its solution. When you name several main ideas, keep each one's details with it.

Explaining how key details support a main idea. Naming a detail is not enough; say how it supports the main idea. A detail can support in different ways: it gives an example, gives a reason or cause, reports a result or measurement, or defines a term the main idea needs. Use the frame: "The detail ___ supports the main idea because it ___." To decide whether a detail is key, use the removal test: imagine deleting it. If the main idea becomes less clear or less convincing, the detail is key. If nothing is lost, it is a minor detail. In the article below, removing "By the fourth week, students found plastic in the bins only twice" from paragraph 4 would leave the reader without proof that the signs and helpers worked, so it is key to that paragraph. In paragraph 1, removing "apple cores, banana peels and bread crusts" loses only examples of scraps, so they are minor details for that paragraph.

Summarizing an informational text. A summary is a short restatement, in your own words, of a text's main ideas and key details, as well as other important information. Other important information is anything a reader needs in order not to misunderstand the text: a condition or rule ("only plant scraps"), a limit on what the evidence shows, a needed definition, or a final result. A summary leaves out minor details, repeated examples and your opinion. It follows the text's order or groups its ideas clearly, and for an article of this length it takes three to five sentences. One condition matters most: a summary that drops a limit can make the text say more than it does. If the author says the students cannot yet tell whether compost helped their tomatoes, a summary that says "the compost made the tomatoes grow better" is wrong, even though every other sentence in it is true.

Original article — From Lunch Scraps to Garden Soil

This article was written for this lesson. Hillview Elementary, its compost project and its numbers are invented.

(1) Every lunch period leaves behind apple cores, banana peels and bread crusts. At most schools these scraps go into the trash. Compost offers another path. Compost is a dark, crumbly material made when tiny living things such as bacteria and fungi, along with worms and insects, break down plant scraps. Gardeners mix it into soil because it adds nutrients and helps the soil hold water.

(2) A compost pile needs a mix of "greens" and "browns." Greens are moist, fresh materials such as fruit peels and grass clippings. Browns are dry materials such as dead leaves and shredded paper. The pile also needs air and some water. Turning the pile with a garden fork lets in air, which helps the living things that do the work.

(3) Last fall the fifth graders at Hillview Elementary set up three bins behind the cafeteria. Students weighed the scraps each day and added dry leaves from the playground as browns. In the first month, the class collected 180 pounds of fruit and vegetable scraps that would otherwise have gone into the trash.

(4) The project almost failed in its second week. Students found plastic forks, yogurt cups and pieces of cheese sandwiches in the bins. Plastic does not break down in a compost pile, and meat and dairy foods can smell and attract animals, so simple bins like Hillview's accept only plant scraps. The class made picture signs for each bin and took turns standing beside the bins at lunch to answer questions. By the fourth week, students found plastic in the bins only twice.

(5) By spring, the first bin had turned into compost, and the class spread it on the school's vegetable beds. The students cannot yet say whether their tomatoes grew better because of the compost, because they did not plant a bed without compost to compare. They plan to try that comparison next year.

Paragraph notes for the article. (1) Compost is made when living things break down plant scraps, and it improves soil. (2) A pile needs greens, browns, air and water. (3) Hillview's class collected 180 pounds of scraps in the first month. (4) Wrong items nearly ruined the bins until signs and helpers fixed the sorting. (5) The compost went on the garden, but its effect is not yet known. Notes 1 and 2 explain what compost is, why it is useful and what a pile needs. Notes 3, 4 and 5 shift from explaining how compost works to telling what happened at Hillview: the collection, the sorting problem and its fix, and the result with its limit. The article therefore develops two main ideas, and it states neither one in a single sentence.

Worked example 1 — Determining the main idea of one paragraph. Paragraph 4. Topic: sorting the bins. Notes on its sentences: wrong items appeared; plastic does not break down, and meat and dairy cause smells and animals; signs and helpers were added; plastic dropped to two finds. Too narrow: "Students found yogurt cups in the bins." Too broad: "Composting is hard." Main idea: "Hillview's compost bins worked only after the class solved a sorting problem with signs and helpers." It covers every note and claims nothing the paragraph does not show.

Worked example 2 — Explaining how key details support a main idea. Main idea A: compost turns plant scraps into material that improves soil, when the pile has what it needs. Detail: "Gardeners mix it into soil because it adds nutrients and helps the soil hold water." It supports the main idea by giving the reason compost is useful. Detail: greens, browns, air and water. It supports the main idea by explaining the conditions a pile needs, which is the "when" part of the main idea. Detail: "Turning the pile with a garden fork lets in air, which helps the living things that do the work." It supports the main idea with a cause: it explains why air is one of the things a pile needs. Removal test: "grass clippings" is only an example of a green, so it is minor.

Worked example 3 — Two main ideas for the whole article. Main idea A (paragraphs 1 and 2): compost turns plant scraps into material that improves soil, when the pile has greens, browns, air and water. Main idea B (paragraphs 3, 4 and 5): Hillview's project turned lunch scraps into compost for its garden, but only after the class solved a sorting problem. Key details for B: 180 pounds of scraps in the first month; signs and helpers cut plastic to two finds; the first bin became compost by spring. Each main idea keeps its own key details. Mixing them, for example by saying that the signs made the compost add nutrients, would join a detail to the wrong idea.

Worked example 4 — A summary with other important information. "Compost forms when bacteria, fungi, worms and insects break down plant scraps, and it improves soil by adding nutrients and helping it hold water, as long as the pile has greens, browns, air and water. Fifth graders at the invented Hillview Elementary collected 180 pounds of scraps in their first month. Their project nearly failed when plastic forks, yogurt cups and pieces of cheese sandwiches got into bins meant only for plant scraps, until picture signs and student helpers cut the plastic to two finds by the fourth week. The class spread its first compost on the garden but cannot yet say whether it helped the tomatoes, because it did not plant a bed without compost to compare." Check: both main ideas, a key detail for each, two pieces of other important information (only plant scraps; the missing comparison), no opinion, no list of every scrap.

Representation task — main idea map. Number the paragraphs of the article. Write a one-line note for each. Draw two boxes for the two main ideas, write each as a complete sentence, and connect each note to the box it supports. Under each box list two key details and label how each supports (example, reason, result or definition). In a third box, write the other important information a summary must keep, and say why a reader would be misled without it.

Independent performance. With your teacher, choose an informational article of four to eight paragraphs from your science or social studies reading. Determine its main idea or main ideas using the four steps, explain in a paragraph how three key details support them, and write a summary of three to five sentences in your own words.

Success criteria: Each main idea is a complete sentence that is neither too narrow nor too broad, and I can show which paragraphs support it. For each key detail I say how it supports the main idea, and I can explain why a detail I left out is minor. My summary includes every main idea, at least one key detail for each, and any condition, limit or result a reader needs; it has no opinion, uses my own words and does not claim more than the article shows.