Main Idea

Main Idea—Teacher Support Notes and Lesson Ideas

What is the main idea?

The main idea of a passage is its central thought or the most important idea. The main idea can usually be summed up in one sentence.

Identifying main idea and supporting details is an important part of reading comprehension. Province-mandated and school board assessments such as EQAO and CASI often test whether or not students are able to find the main idea in a piece of writing and identify the information that supports it.

Is the main idea the same as the topic?

The topic and main idea are related by are not necessarily the same thing. The topic of an article for example, might be dinosaurs, but the main idea might be about the possible reasons that animals become extinct.

What is a supporting detail?

A detail is an idea or fact that explains or backs up the main idea. A supporting detail gives more information about the main idea through example. Teachers often ask students to provide supporting details when they are answering questions from a work of fiction.

What is evidence?

Providing evidence is the same as supplying supporting details. Evidence consists of facts, expert opinions, quotable comments, clarifying examples, anecdotes, or illustrations that support the main idea. Teachers often ask students to provide evidence when they are answering questions from a work of non-fiction.

Evidence can be in the form of:

Facts: names, dates, specific events, quotations or examples

Authoritative Opinions: what an “expert” says

Why is evidence and supporting detail important when you are explaining the main idea?

Evidence and supporting detail is important to illustrate, prove or back up what you are saying about the main idea of the article or story.

Tools for Teaching Main Idea and Supporting Detail

 Main idea “survival” activity

Target grade: 3-5

Each student is given a photocopied non-fiction article and the teacher reads the article aloud. Each student has another sheet of paper with a three tables on it: one has 20 cells, one has 10 cells and one has 5 cells.

Students individually pick 20 words which they believe capture the main idea of the article. These words are often nouns and verbs. Give the students a time limit for this activity.

Then the students individually “vote 10 words off the island” and place the words on the table with 10 spaces.

Pairs or small groups then have a discussion about their 10 words. This part of the activity is where students begin to defend and justify their choices. The groups or pairs agree and the final version goes onto the last 5 cell grid, further reducing the word quota.

Each student then uses the five words to write a sentence that captures the main idea. Some linking words must be added back to make the sentences flow. Sentences are read aloud.

Important Ideas/ Interesting Ideas

Target Grade: 4-8

Teacher models the strategy of coding a text with two different coloured highlighters representing interesting and important ideas. (critical vs. non-critical information) The teacher then provides each pair of students with a different text selection and two different coloured highlighters and the team tries the strategy. Remind the students that interesting ideas relate to the main idea but could safely be left out if we summarized the text. When the students have completed the task there is a whole class debrief and the teacher then provides a clean copy for each student to mark up after the “group think.”

Enlarging the Text

Target Grade: 4-8, students below grade level

The teacher retypes a portion of a text and enlarges and or bolds vocabulary and main concepts so that the text features highlights critical information. Then the students do the “important ideas/interesting ideas” activity or the “shrink write” activity.

  1. Brainstorm words for a topic.
  2. Write for a brief period of time using your brainstormed ideas.
  3. Read what you have just written and highlight or underline your favourite parts.
  4. Reduce your writing to a series of single words or short phrases arranged down the page to create a free-verse poem.


 Students capture the essence of the main idea by creating a frozen-action performance. The tableaux can be an excellent pre-writing activity for students struggling with main idea.

Sketching the Main Idea

Students illustrate the most powerful idea in the text.

Poetic Devices which help students with Main Idea

When students are trying to figure out the main idea of a poem, it helps to focus on literary devices that give us clues about the gist of the poem. Some of these include:

Poetic Device Definition Why it helps with main idea Example
Alliteration Repetition of sounds (usually at the beginning of each word) to create an effect The effect usually gives you a clue about the main idea Repetition of the letter “s” in a line about walking through a forest might emphasize the quietness of the experience
Onomatopoeia Words that sound like the item being described The example usually gives you a clue about the main idea Baa Baa black sheep
Simile Comparison using the words like or as The comparison helps the reader make a connection to the main idea She was as quiet as a mouse
Metaphor Comparison where one thing is said to be another (usually the two items are not normally compared) The comparison helps the reader think of why the two items are related and this often helps with understanding the main idea Crocodiles’ teeth are white daggers.
Repetition Repeating words or phrases for effect The effect often reflects or gives a clue to the main idea The kite looped and dove, looped and dove

 Headline Writer

The author of a newspaper article rarely writes his/her own headlines. A headline writer reads someone else’s article and tries to sum up the main idea in 5-8 words.

1. Show students a short text selection and read it to them.

2. Model how you might generate a good headline that captures the gist of the article. (include some lousy tries)

3. Try another and get students to help.

4. Put students into groups and have them generate headlines for an article. (It’s fun to reveal later what the headline actually was.)

5. Have students justify why they think their headline reflects the main idea.

Main Idea Sentence Stems

The most important thing I remember about this text is…

The main message is…

The text was mainly about…

Clues, words and features that helped me understand the text were…

 Question to Statement

Turn a question into a statement and add a justification. For example:

Question: Should kindergartens eat only healthy snacks at school?

Statement with a justification: Kindergartens should only eat healthy snacks at school because school is a place where we are educated and part of a good education is knowing how to eat what is good for our bodies.

Justification Stems

Provide sentence stems which require students to provide a supporting detail. The stems can be anything that relates to the material you are covering.


Turn of the lights when you leave a room because…(provide reason/justification)

Pack your backpack the night before school because…(provide reason/justification)

Students also like to write sentence stems with a partner. Remind them that the stem must guide the reader with a clue. In the first example above, the words “when you leave a room” gives the reader the idea that the supporting detail might have to relate to the fact that lights don’t need to be left on if nobody is in the room. In the second example, the words “the night before school” gives the reader the idea that the supporting detail might have to be something about thinking ahead.

Text feature as persuasion

Have groups of students practice gathering evidence. Give them a selection of catalogues and have them choose one item from a page that they’d like to buy. Ask them to pick an item which they believe the advertisers did a good job at selling. Set a specific time limit of about 5-10 minutes. Have the students identify the text features that were used by the advertisers to persuade the buyer. Use the following graphic organizer:

Text Feature that helps sell the product Reason why it persuades or influences the buyer
Example: Close-up photo of the bottom of a skate board Example: Shows a picture of a skull stencil which might appeal to a skater who likes doing dangerous tricks

Once the group has identified 4 or 5 reasons why the text features persuade or influence the buyer, have them pick the two best. (Ranking is a good way for students to practice the skills of condensing and prioritizing which are critical components of the summarization strategy.)

Have one member of the group present the supporting evidence to the class.

 Subject Specific Vocabulary

Picking out subject-specific vocabulary in a non-fiction text selection can often help students pick out supporting details that support the main idea. Explaining the subject-specific vocabulary in everyday language helps students make connections to the main idea, grounding their understanding. Here’s an example:

Subject-specific vocabulary related to the main idea What the word means in everyday language
Example: Space Junk Garbage left orbiting in space from things like satellites we’ve sent up and no longer use or are broken
Example: Autopsy A doctor that examines a dead body to see what caused the death

Getting students to use synonyms is a great way of checking comprehension.

Main Idea and Supporting Details Place Mat

 Provide students with a large piece of chart paper and have one student sit in front of each of the sections. Have the students agree on the main idea of the text selection you have given them and write it in one sentence in the middle of the paper. Have each student jot down details from the text selection that might support the main idea. Have the students share their ideas and underline or highlight which details best support the main idea.

The place mat activity can be modelled by you, practiced in groups and done as independent practice. The facts, names, dates, and quotations from experts categories can be changed according to the kind of text selection you have given the students. The example above works well for a non-fiction article which includes quotations from experts.

Main Idea Graphic Organizer

Have students pick out 6 key words from the text selection. Students then add 3 supporting details that link to the key words. At the bottom of the page students use some or all of the key words and their two best supporting details to write out the main idea.









Main Idea Twitter

Challenge your students to state the main idea in one sentence with proper grammar, spelling and punctuation in a 140 character Tweet”.  (This paragraph has 137 characters!)

If students are unable to do this on their phones due to protocol, have them do it on computers with a character count function otherwise the counting of characters will be too time consuming.

Main Idea Criteria in writing

What are we looking for in a piece of writing that has a strong main idea?

-The writer clearly states the main idea

-The supporting evidence relates to the main idea

-The writer is able to generalize e.g. understand the enduring understanding or the lesson or the big picture of the text selection.

-The writer uses language that represents facts in an impersonal style e.g. “The author says,” or “Many argue that” or “It seems that” instead of “I think”

-The writer uses a range of linking words to indicate cause and effect, problem and solution, compare and contrast

 What might an accomplished writer include?

-The accomplished writer might clearly state the main idea and preview evidence that will follow

-The accomplished writer might reiterate the main idea and make an evaluative statement

 Please click on link below for Word format:

Main Idea—Teacher Support Notes and Lesson Ideas

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