The three parts
| Part | Job | Length |
|---|---|---|
| Hook | Make the reader want to keep going | One or two sentences |
| Background | Give the context needed to understand your claim and why it matters | Two or three sentences |
| Thesis | State your claim and reasons | One sentence, sometimes two, at the end |
Purdue OWL describes the same shape for an argument essay: set the context, explain why the topic matters, then present the thesis.
Weak vs strong hooks
| Weak | Strong | Why |
|---|---|---|
| Since the beginning of time, people have needed water. | Last month, our school's vending machines sold more than 3,000 bottles of soda. | Sweeping claims say nothing. A specific number about your topic does. |
| Webster's dictionary defines courage as... | My grandmother crossed the border at sixteen with one suitcase and no English. | Dictionary openings are overused. A specific scene pulls the reader in. |
| Have you ever wondered about fire? | In June 2023, smoke from wildfires in Canada turned the sky over New York City orange. | A vague question invites a shrug. A vivid real event makes the topic matter. |
Worked examples
Example 1: rebuild a weak introduction
Problem Since the beginning of time, schools have had rules. Rules are important. In this essay I will talk about phones in school.
- Replace the broad opener with something specific from your school or your life: Last week, three phones buzzed during our chemistry quiz.
- Add the background a reader needs: Our school lets students keep phones in their pockets during class, and teachers spend minutes each period asking students to put them away.
- Replace the announcement with a real thesis: Phones should be stored in lockers during class, because they distract students and make it easier to cheat.
Answer Last week, three phones buzzed during our chemistry quiz. Our school lets students keep phones in their pockets during class, and teachers spend minutes each period asking students to put them away. Phones should be stored in lockers during class, because they distract students and make it easier to cheat.
Example 2: write the introduction last
Problem You do not know how to start. What can you do?
- Write a rough thesis and the body paragraphs first.
- Look through your body paragraphs for the most striking fact, example or moment. That is often your best hook.
- Then write the introduction around it and polish the thesis so it matches what you proved.
Answer Many writers draft the introduction last, once they know what the essay argues.
Common mistakes and fixes
| Mistake | Fix |
|---|---|
| Opening with a huge claim about all of history or all people | Open with something specific: a fact, a moment, a person. |
| An introduction that is a third of the essay | Cut background to what the reader needs. Details belong in the body. |
| Announcing the essay (In this essay I will) | Just state your claim. |
| A hook that has nothing to do with the thesis | Pick a hook that leads naturally into your topic. |
| No thesis at all | End the introduction with one clear claim. |
Practice
Five introduction questions
Which opening breaks this page's advice by starting too broad?
- In June 2023, wildfire smoke from Canada turned New York City's sky orange.
- Last month, our school's vending machines sold more than 3,000 bottles of soda.
- At 6:10 every morning, my bus pulls up before the sun does.
- Since the beginning of time, people have used technology.
Show answer
Answer: Since the beginning of time, people have used technology.
It makes a sweeping claim about all of history and says nothing specific. The other three open with a concrete number, scene or event.
What should the last sentence of an introduction usually be?
- A dictionary definition
- The thesis
- A summary of every body paragraph's evidence
- A question for the reader
Show answer
Answer: The thesis
The introduction moves from hook to background to claim, so the thesis comes last. Evidence belongs in the body, and a question is not a claim.
In this introduction, which sentence gives background? (1) Last month, our school's vending machines sold more than 3,000 bottles of soda. (2) Most of those machines sit in the cafeteria, where every student eats lunch. (3) The school should replace soda in its machines with water and milk, because sugary drinks hurt students' health and focus.
- Sentence 1
- Sentence 2
- Sentence 3
- None of them
Show answer
Answer: Sentence 2
Sentence 1 is the hook (a striking number), sentence 3 is the thesis (a claim with reasons), and sentence 2 gives context the reader needs to understand the claim.
Your introduction is 300 words in a 600-word essay. What is the best fix?
- Add a second hook
- Make the font smaller
- Remove the thesis to save space
- Cut the background to what the reader needs and move details into the body
Show answer
Answer: Cut the background to what the reader needs and move details into the body
An introduction should be short, and extra details are evidence that belongs in the body. A second hook adds length, and the thesis must stay.
Which hook best fits a serious essay about wildfire safety, following this page's advice?
- In June 2023, smoke from wildfires in Canada turned the sky over New York City orange.
- Have you ever wondered about fire?
- Webster's dictionary defines fire as the light and heat of burning.
- What is your favorite kind of campfire snack?
Show answer
Answer: In June 2023, smoke from wildfires in Canada turned the sky over New York City orange.
It is a specific, real event tied to the topic. The page warns against vague questions and dictionary definitions, and a snack question does not fit a serious tone.
Frequently asked questions
How long should an introduction be?
For a five-paragraph school essay, usually three to five sentences, or about 10% of the essay. Longer papers may need a longer introduction, but the rule is the same: hook, the background a reader needs, and the thesis. If it takes more space than a body paragraph, trim it.
Can I start with a question?
Yes, if it is specific and real, like Why does our town have two libraries but no pool? Avoid vague ones like Have you ever wondered...? A question cannot be your thesis, so answer it by the end of the introduction.
Should I write the introduction first or last?
Either works. Many writers draft a rough thesis first, write the body, then come back to write the hook and background, because by then they know what the essay really argues.
Sources
- Purdue OWL, Argumentative Essays, accessed October 1, 2026
- Purdue OWL, Argument Papers, accessed October 1, 2026
