Level 03 – Step 08 : Modal Must for Obligation (We must protect nature. You mustn’t bully.)
/Level 03 – Step 08 : Modal Must for Obligation (We must protect nature. You mustn’t bully.)
🚪 Let’s Begin
/🚪 Let’s Begin
🦉Professor Owl: Today we will learn how to use the modal verb must to talk about obligations and rules.
/🦉Professor Owl: Today we will learn how to use the modal verb must to talk about obligations and rules.
🐧Igupen: Must sounds strong. Is it like something we have to do?
/🐧Igupen: Must sounds strong. Is it like something we have to do?
🦉Professor Owl: Yes. Must shows a strong obligation or rule.
/🦉Professor Owl: Yes. Must shows a strong obligation or rule.
📚 Lesson
/📚 Lesson
What does must mean?
/What does must mean?
• Must is a modal verb we use to say someone has to do something.
/• Must is a modal verb we use to say someone has to do something.
• Mustn’t (must not) shows prohibition — something is not allowed.
/• Mustn’t (must not) shows prohibition — something is not allowed.
How to make sentences with must
/How to make sentences with must
• Affirmative: Subject + must + base verb. Example: We must protect nature.
/• Affirmative: Subject + must + base verb. Example: We must protect nature.
• Negative: Subject + mustn’t + base verb. Example: You mustn’t bully.
/• Negative: Subject + mustn’t + base verb. Example: You mustn’t bully.
When to use must for obligation
/When to use must for obligation
1. For rules or laws: You must wear a seatbelt.
/1. For rules or laws: You must wear a seatbelt.
2. For strong advice or necessity: I must finish my homework tonight.
/2. For strong advice or necessity: I must finish my homework tonight.
3. For moral duties: We must protect nature.
/3. For moral duties: We must protect nature.
🦉Professor Owl’s one-point tip
/🦉Professor Owl’s one-point tip
Use must for strong, important obligations. Use mustn’t to warn about things that are forbidden or dangerous.
/Use must for strong, important obligations. Use mustn’t to warn about things that are forbidden or dangerous.
Quick checks inside the lesson
/Quick checks inside the lesson
We must protect nature → strong duty for everyone.
/We must protect nature → strong duty for everyone.
You mustn’t bully → clear rule: bullying is not allowed.
/You mustn’t bully → clear rule: bullying is not allowed.
I must go now → personal necessity.
/I must go now → personal necessity.
🌼 Sample Sentences
/🌼 Sample Sentences
No.01 We must protect nature.
/No.01 We must protect nature.
No.02 You mustn’t bully other children.
/No.02 You mustn’t bully other children.
No.03 Students must wear their school uniforms.
/No.03 Students must wear their school uniforms.
No.04 I must finish my homework before dinner.
/No.04 I must finish my homework before dinner.
No.05 You must wash your hands before eating.
/No.05 You must wash your hands before eating.
No.06 People must follow traffic lights.
/No.06 People must follow traffic lights.
No.07 She must see a doctor if she is very sick.
/No.07 She must see a doctor if she is very sick.
No.08 We mustn’t waste water.
/No.08 We mustn’t waste water.
No.09 He must apologize for breaking the rule.
/No.09 He must apologize for breaking the rule.
No.10 Visitors must show their ID at the gate.
/No.10 Visitors must show their ID at the gate.
🎓 Practice exercises
/🎓 Practice exercises
Note: Think first, then check the answers.
/Note: Think first, then check the answers.
Q1: Make an obligation sentence: (you / must / be / on time)
/Q1: Make an obligation sentence: (you / must / be / on time)
Q2: Choose correct form: They (must / mustn’t) park here.
/Q2: Choose correct form: They (must / mustn’t) park here.
Q3: Fill in the blank: You ___ (not / must) feed the wild animals. (use mustn’t)
/Q3: Fill in the blank: You ___ (not / must) feed the wild animals. (use mustn’t)
Q4: True or False: Use must for a strong rule or law.
/Q4: True or False: Use must for a strong rule or law.
Q5: Change to negative prohibition: People must stop smoking here.
/Q5: Change to negative prohibition: People must stop smoking here.
Q6: Make a sentence of necessity: (I / must / study / for / test)
/Q6: Make a sentence of necessity: (I / must / study / for / test)
Q7: Choose the correct sentence: A) She musts wear a helmet. B) She must wear a helmet.
/Q7: Choose the correct sentence: A) She musts wear a helmet. B) She must wear a helmet.
Q8: Fill in the blank: We ___ (protect) our environment. (use must)
/Q8: Fill in the blank: We ___ (protect) our environment. (use must)
Q9: Make a prohibition sentence: (they / not / must / cross / here)
/Q9: Make a prohibition sentence: (they / not / must / cross / here)
Q10: Question about obligation: (must / we / bring / our passports)
/Q10: Question about obligation: (must / we / bring / our passports)
Answers
/Answers
A1: You must be on time.
/A1: You must be on time.
A2: mustn’t → They mustn’t park here.
/A2: mustn’t → They mustn’t park here.
A3: mustn’t → You mustn’t feed the wild animals.
/A3: mustn’t → You mustn’t feed the wild animals.
A4: True → Use must for strong rules or laws.
/A4: True → Use must for strong rules or laws.
A5: People mustn’t smoke here.
/A5: People mustn’t smoke here.
A6: I must study for the test.
/A6: I must study for the test.
A7: B is correct → She must wear a helmet.
/A7: B is correct → She must wear a helmet.
A8: We must protect our environment.
/A8: We must protect our environment.
A9: They mustn’t cross here.
/A9: They mustn’t cross here.
A10: Must we bring our passports?
/A10: Must we bring our passports?
🦉 Closing
/🦉 Closing
🦉Professor Owl: Excellent work today. When a rule is strong or something is necessary, use must. When something is forbidden, use mustn’t.
/🦉Professor Owl: Excellent work today. When a rule is strong or something is necessary, use must. When something is forbidden, use mustn’t.
Try making five sentences about rules at school or home.
/Try making five sentences about rules at school or home.
Keep practicing and you will feel confident using must and mustn’t.
/Keep practicing and you will feel confident using must and mustn’t.
