“Can vs Could: 19 Key Points to Master English Modal Verbs”

 

Maximizing Potential: Why “Can” and “Could” Matter — A Complete Guide for ALTs and Students

A friendly, practical guide filled with classroom activities, dialogues, cultural tips, and real-life examples so your students can use these little words with confidence.

As an Assistant Language Teacher (ALT), you know how one tiny word can change a sentence from blunt to polite, from awkward to natural. “Can” and “could” are three and five letters, but they carry huge power: permission, ability, possibility, politeness, and imagination. This guide will take you from simple explanations to classroom activities and real conversations your students will actually use.

1. Meet the Words: What “Can” and “Could” Do

At the surface level:

• Can → present ability, general possibility, permission, informal requests.
• Could → past ability, polite requests, conditional/hypothetical meanings, and possibility with a softer tone.

“Small words, big confidence. Teach them well and students will open more doors—socially, academically, and professionally.”

A quick table to remember

Use	Can	Could
Present ability	I can swim.	—
Past ability	—	I could swim when I was young.
Polite request	Can you help me?	Could you help me? (more polite)
Possibility	It can get cold in winter.	It could rain tomorrow.
Hypothetical / Conditional	—	If I had time, I could learn Spanish.

2. Why Your Students Struggle (and how to help)

Many students learn a single use of these modals and then stop. That leads to mistakes like:

“You can give me your pen.” (This sounds like an order.)

Explain tone and intent. English often values indirectness when asking, and small changes make big differences:

• “Can you lend me your pen?” — casual, common.
• “Could you lend me your pen?” — softer, more polite.
• “May I borrow your pen?” — formal and polite.

Teach with contrast

When a student says “You can give me your pen,” demonstrate how the sentence feels and then model the polite version. Role play it. Students understand through feeling and practice, not just rules.

3. Deep Dive: All the Ways to Use Can

Ability (present): “I can ride a bike.” Clean and direct.

Possibility/general truth: “Electric scooters can be fast.” This expresses general facts.

Permission: “Can I go to the bathroom?” — common with children and casual contexts.

Informal request: “Can you pass the salt?” in a family or close friends setting (a direct but usually polite ask).

Classroom idea: Can Chart

Write a big chart with columns: Can / Can't / When I can. Students add lines like: “I can cook rice,” “I can't drive,” “I can read English at home.” Share in pairs for fluency practice.

4. Deep Dive: All the Ways to Use Could

Past ability: “When I was small, I could climb trees.”

Polite request: “Could you close the door?” (More polite than “Can you…”.)

Possibility / uncertainty: “It could rain this afternoon.” Softer than “It will rain.”

Hypothetical / conditional: “I could help you if I had time.” This opens imagination or conditional action.

Activity — Past Stories
Ask students to tell one thing they could do when they were younger but can’t do now, and one thing they wish they could do in the future. Have them use “I could…” and “I wish I could…”. Share with the class.

5. Can vs Could — Tone, Politeness, and Context

One sentence can sound very different with a modal change:

Student: “Can I have a day off?”

Teacher: “Yes, that’s fine.”

versus

Student: “Could I please have a day off?”

Teacher: “Of course — thanks for asking politely.”

Here, “could” adds politeness and distance — useful for formal emails, older people, or when the request is sensitive.

6. Classroom Activities That Work (step-by-step)

Activity A — Role Play Café (Beginner)

1. Set up “tables” in the class. Give students menus with prices.
2. Pairs: one is server, one is customer. Students must order using “Can I have…” or “Could I have…”.
3. Swap roles. Encourage natural mistakes and then correct politely.

Tip: Model 3 example dialogues first. Use simple props — a paper cup and play money.

Activity B — Show & Tell: What I Can Do

1. Ask each student to prepare a short 1–2 minute demo: “I can…”.
2. Encourage questions from classmates using “Can you…?” and “Could you…?”.

Activity C — Future Possibilities Brainstorm (Intermediate)

Groups brainstorm ideas starting with “We could…” — make a poster of travel plans, charity ideas, or a class festival. This practice builds conditional and imagination use.

Activity D — Politeness Ladder (Advanced)

Write one request on the board (e.g., “borrow your book”), and have students rewrite it in five levels of politeness:

1. Give me your book.
2. Can I borrow your book?
3. Could I borrow your book?
4. Would you mind if I borrowed your book?
5. Is it possible for me to borrow your book?

Discuss when each level is appropriate (friends, teachers, formal letters).

7. Real-World Application: Where Students Use These Words

When practicing these modals, point out real situations:

• Job interviews: “I can meet deadlines.” / “I could manage a small team.”
• Travel: “Can you tell me where the station is?” / “Could you recommend a good hotel?”
• Shopping: “Can I try this on?” / “Could I pay by card?”
• Everyday life: “Can you show me?” / “Could you please explain?”

Dialogue examples — practical

You: “Could you tell me how to get to the station?”

Local: “Sure. Go straight two blocks and turn left.”

Interviewer: “Can you give an example of when you handled a problem at work?”

Candidate: “Yes — I can describe a time when our printer broke down and I coordinated a fix.”

8. Common Errors & How to Correct Them Gently

ALTs need correction strategies that help, not embarrass. Try these techniques:

• Recast — repeat correctly without highlighting the error. Student: “You can give me your pen.” Teacher: “Could you lend me your pen? Sure, here you go.”
• Clarify question — ask a follow-up to guide them: “Do you mean ‘Can I borrow your pen?’”
• Mini lesson — pause the class and show direct comparison examples for 3 minutes.

9. Using Technology to Practice

There are many free and low-cost tools to help students practice modal verbs outside class:

• Quizlet — make flashcard sets: “Can = present ability.”
• Kahoot — quick quizzes with instant feedback and competition.
• Language exchange apps — encourage students to ask for help in real-life conversations using “Could you…?”
• Chatbot practice — short scripted prompts for polite requests, e.g., “Could you tell me the weather?”

10. Nuances for Advanced Learners

When students reach a higher level, explore subtleties:

• Can’t vs couldn’t: “That can’t be true” (present impossibility). “He couldn’t have known” (past impossibility).
• Could have + past participle: “I could have called, but I forgot” (regret or missed possibility).
• Would you mind…? vs “Could you…?” — more formal and indirect.
• May/might/ could: compare levels of certainty: may (slightly formal), might (less certain), could (possible but not certain).

11. Cultural Notes: Politeness Across Languages

Direct translation causes mistakes. In Urdu, Japanese, or other languages, permission and politeness may use different structures or cultural markers. Students who translate directly can sound too blunt in English. Address this with:

• Contrastive examples: show how a phrase sounds in both languages.
• Role play formal vs casual settings so students “feel” the tone.
• Encourage students to use “could” in formal emails and “can” with close friends.

Classroom example — cultural contrast

Ask students how they would ask a teacher for a day off in their language, then write possible English versions and discuss which is most polite in an English-speaking workplace.

12. Long Scenarios — Practice Dialogues You Can Use Whole Class

Scenario: At the Airport

You: “Excuse me — could you tell me where gate 12 is?”

Staff: “Sure. Go down this hall, turn right, and it’s the third gate on the left.”

You: “Thank you. Can I check this bag here?”

Staff: “Yes, you can check it at counter 5.”

Scenario: Job Interview

Interviewer: “Can you tell me about a time you solved a problem?”

Candidate: “Yes — I can discuss a project where I found a cheaper supplier and saved money.”

Interviewer: “Could you give specifics of the savings?”

Candidate: “Of course. I could reduce costs by 12% in the first quarter.”

Scenario: In Class — Asking for Clarification

Student: “Can you explain that grammar rule again?”

Teacher: “Sure — I can give another example.”

Student: “Could you show it on the board?”

Teacher: “Yes, of course.”

13. Assessment Ideas — How to Check Progress

Use both speaking and writing checks:

• Speaking: Quick 1-minute role-play cards with prompts (“Ask for the menu,” “Ask to borrow a pen”).
• Writing: Short paragraph using at least five sentences with “can / could / could have.”
• Peer feedback: Partners check politeness levels and suggest changes.

14. Tips for ALTs — Keep Students Confident

• Always model first — show natural examples and repeat them naturally.
• Correct through recast — avoid public embarrassment.
• Use praise. Acknowledge effort: “Nice! Your question sounded very polite.”
• Mix controlled practice (worksheets) with freer practice (role plays) every class.

15. Extra Practice — Homework & Takeaway Tasks

1. Write 8 sentences: 4 with “can” (present ability) and 4 with “could” (past, polite, or conditional).
2. Record a 1-minute voice message asking for information using “Could you…?” and send it to the teacher or partner.
3. Find one example of “could” or “can” in a real video or song and explain the meaning in 2 sentences.

16. Final Thought — Empowerment Through Small Words

Teaching “can” and “could” is low effort but high reward. These words let students ask for help, describe abilities, imagine possibilities, and act politely in social and professional life. As ALTs, your job is to make those three or five letters feel natural and safe.

Quick Classroom Summary — 5 Activities to Try Tomorrow

1. Role Play Café (Beginner) — practice ordering and polite requests.
2. Show & Tell (Can / Could) — build confidence and fluency.
3. Politeness Ladder — rewrite requests at different politeness levels.
4. Future Brainstorm (We could…) — practice conditional and imagination.
5. Mini Interview Role Play — use “can” and “could” for job phrases.

17. Call to Action

Try one activity in your next class. Observe which form your students use most and why. When they make mistakes, use those moments — gently — to teach tone and culture. Over time, students will not only learn the forms; they’ll learn how to connect, ask kindly, and imagine possibilities.

Try an activity now — ask your class to use one “could” sentence each

18. Resources & Further Reading

(If you want, I can prepare a printable worksheet or a downloadable PDF version of this lesson that includes role-play cards and a teacher's answer key.)

19. Closing — A Small Story

Last year I had a shy student, Aisha, who always said things like, “You can help me?” She meant to be polite but it sounded like a demand. So we practiced in a gentle way — a role play where she asked for a book, and I answered in different tones. She tried “Could you…?” and the whole class smiled when they heard the soft, polite phrasing. She beamed. That small change helped her speak up in group work and later ask the principal politely for permission to lead a project. Tiny words, big confidence.

Now it’s your turn: Choose one activity, try it in class, and share the experience with other ALTs. These words are tiny tools that build real life skills.

Written for ALTs and ESL teachers — adapt freely for your classroom. If you’d like this converted to a printable PDF or HTML with images and role-play cards included, reply “PDF please” or “Add images.”

Happy teaching — you can make a big difference with small words!