Modals of Obligation, Necessity & Advice

Target Structures:

Must / Have to / Don’t have to / Mustn’t / Should / Ought to / Need to / Didn’t need to

Goal:

Use modal verbs correctly to express rules, duties, necessity, and give advice confidently in conversation.

1. Warm-Up (3 min)

🗣️ Questions:

1. What are some rules you must follow at work or school?

2. What is something people don’t have to do but often do anyway?

3. What advice would you give someone starting a new job?

💬 Sample Answer:

At my job, I have to arrive on time. You don’t have to wear formal clothes, but you should look tidy.

🎯 Focus: get students using modals in context from the start.

2. Presentation (8 min)

A. Obligation and Necessity

✅ Must / Have to / Need to → obligation, rules, necessity

• Must – strong personal obligation (speaker’s opinion)

  You must wear a helmet. (It’s really important!)

• Have to – external obligation (a rule or law)

  You have to show your ID to enter.

• Need to – necessity, something required

  I need to study for my test.

❌ Mustn’t – prohibition (not allowed)

You mustn’t use your phone during class.

✅ Don’t have to / Don’t need to → lack of necessity

You don’t have to come if you’re busy. (It’s optional.)

B. Advice

✅ Should / Ought to → recommendation, good idea

You should see a doctor.
You ought to get more rest.

🧠 Note: “Should” is more common in everyday speech; “ought to” sounds slightly more formal.

C. Past Forms

✅ Had to → past obligation

I had to do my homework before dinner.
✅ Didn’t need to / Didn’t have to → past lack of necessity
We didn’t need to cook; my dad ordered pizza.

3. Controlled Practice (6 min)

Complete the sentences with the correct modal verb.

1. You ______ (not / park) here. It’s forbidden.

2. She ______ (study) hard if she wants to pass.

3. We ______ (not / go) to the meeting yesterday — it was cancelled.

4. You ______ (take) an umbrella. It looks like rain.

5. He ______ (wear) a uniform at his old job, but now he doesn’t.

6. You ______ (be) careful when crossing the road.

7. You ______ (not / tell) anyone — it’s a secret!

8. I ______ (get up) early tomorrow; my train leaves at 7.

✅ Answer Key & Explanations

1. mustn’t → expresses prohibition (not allowed).

2. has to / must / needs to → shows obligation or necessity.

3. didn’t have to / didn’t need to → there was no need, the event was cancelled.

4. should / ought to → giving advice (good idea to take one).

5. had to → past obligation, no longer true.

6. must / have to → strong necessity (safety rule).

7. mustn’t → forbidden action.

8. have to / need to → obligation about the future.

🧩 Why others are wrong:

• “Don’t have to” means optional, not forbidden.

• “Shouldn’t” means not a good idea, not prohibited.

• Using present instead of past breaks time consistency.

4. Interactive Practice (5 min)

Complete the sentences with your own ideas.

1. You mustn’t ______ in a library because ______.

2. You should ______ if you feel stressed.

3. People have to ______ when they travel abroad.

4. You don’t have to ______ on weekends, but I often do.

5. I need to ______ before I can relax tonight.

💬 Example:

You mustn’t shout in a library because it’s a quiet place.

🎯 Focus: use each modal naturally in context.

5. Free Practice (4 min)

🗣️ Real-Life Scenarios:

Discuss and decide what’s necessary or optional in these situations:

1. A student preparing for an exam

2. A person renting a new flat

3. A tourist visiting a foreign country

4. Someone starting a healthier lifestyle

💬 Example:

When you travel abroad, you have to bring your passport, and you should learn a few local words.

🎯 Encourage full-sentence responses mixing “must”, “should”, “don’t have to”.

6. Extra Discussion (3–4 min)

💬 Conversation Questions:

1. What’s something you must do every day?

2. What’s something you don’t have to do but still choose to?

3. What’s the best piece of advice you’ve ever received?

4. What’s a rule you think people shouldn’t have to follow? Why?

5. Do you think people today feel more or less pressure to follow rules?

🎯 Encourage opinion-based answers and examples.

7. Wrap-Up & Review (2 min)

🎯 Quick Recap:

• Must / Have to / Need to → express obligation or necessity

• Mustn’t → prohibition

• Don’t have to / Don’t need to → no obligation

• Should / Ought to → advice or recommendation

• Had to → past obligation

• Didn’t need to → past lack of necessity

💬 Mini Challenge:
Tell me two things you must do and one thing you don’t have to do today.