Certainty Modals Teacher Guide TEACHER GUIDE: THE CERTAINTY SCALE
Lesson 1: Expressing Certainty with Modal Verbs
Top Secret / Teacher Only
Instructional Objective
Students will be able to distinguish between different levels of certainty using the modal verbs must, might / could, and can't. They will apply these verbs to make deductions based on sensory and visual evidence.
The Mystery Box Hook (15 mins)
Prepare a box with a hidden object inside (e.g., a bell, a sponge, a set of keys). Provide a "Detective Notebook" feel by asking students to write their observations first.
Step 1: Shake the box. Ask: "What do you hear?"Step 2: Model the language: "It might be a bell, but it can't be a pillow because it's too noisy."Step 3: Pass the box. Students use the target grammar to guess.
Direct Instruction: The Certainty Meter
100% Sure Yes
MUST
Maybe (50%)
MIGHT / COULD
100% Sure No
CAN'T
ESL Scaffolding
Visual Support: Use emojis for certainty (✅ ❓ ❌).
Sentence Starters:
Common Error: Students often use "can't" to mean "not allowed." Remind them that here it means "impossible."
PREP CHECKLIST
Opaque box + mystery object
Lesson 1 Slides (Ambiguous Images)
Detective Notebook Worksheets
Differentiation Strategies
Emerging Learners
Provide a word bank of objects for the mystery box. Allow them to use single-word guesses before pushing for the full sentence structure: "Must be keys!" → "It must be keys."
Advancing Learners
Challenge them to use "may" or "may not." Ask them to provide two pieces of evidence for every deduction using "because."
Certainty Modals Slides Grammar Detective Agency
THE CASE OF THE
MISSING CLUES
Lesson 1: Mastering Degrees of Certainty
Observe
Deduce
Report
Hook: The Mystery Box
What's Inside?
Listen to the sound...
1 "It must be..."
2 "It might be..."
3 "It can't be..."
❓
The Certainty Meter
MUST
100% Certain YES
"I see whiskers and hear meowing... It must be a cat!"
Might / Could
Maybe / 50-50
"I see a tail, but no head. It might be a dog, or it could be a fox."
Can't
100% Certain NO
"It has six legs. It can't be a bird! Birds only have two."
Case File #1
The Shadow Puzzle
Look at the shadow on the wall. What do you see?
Discussion Questions:
What MUST it be? Why?
What MIGHT it be? What else?
What CAN'T it be?
Detective Protocol
EVIDENCE
What do you see, hear, or feel?
DEDUCTION
Use "must", "might", or "can't".
REASON
Explain why using "because".
Let's solve the next mystery!
Detective Notebook Worksheet Detective Notebook
CASE FILE #2026-01: THE CERTAINTY SCALE
Agent:
Date:
Mission 1: The Mystery Box
Draw your clue here
Write your deductions:
100% Sure Yes
It must be __________________________
Maybe / Possible
It might be __________________________
100% Sure No
It can't be ___________________________
Mission 2: Photo Analysis
👣
Evidence A: Wet footprints lead to the kitchen.
must
might
🪟
Evidence B: A broken window and a baseball on the floor.
can't
must
Detective Tip:
Always use BECAUSE to explain your thinking!
Property of Detective Agency 4B
Crime Scene Slides The Evidence Lab
Lesson 2: Formulating Logical Deductions
The Deduction Formula
SUBJECT
The Person or Thing
MODAL
Must / Might / Can't
VERB
Base Form (No 's')
"He must be tired."
"He must is tired."
Scenario 1
The Messy Kitchen
Clues:
An empty milk carton on the floor.
Paw prints on the counter.
The back door is open.
"The cat must ______ the milk."
"A thief might ______ through the door."
🥛 🐾 🚪
TOP SECRET
Your Turn, Detectives!
Look at your Deduction Log . We will examine three more scenes. Write one must, one might, and one can't sentence for each.
Scene 1:
Scene 2:
Scene 3:
Self-Check List
1
Did I use a Subject (He, She, It, They)?
2
Did I pick the right Modal level?
3
Is my verb in the BASE form?
Deduction Log Worksheet DEDUCTION LOG: CASE SCENARIOS
Grammar Detective Agency • Unit 2
Agent Name:
Scene 1: The Empty Cage
LEVEL: INTERMEDIATE
Evidence Found:
Hamster cage door is open.
Seeds on the carpet.
A small brown blur under the sofa.
Formal Deductions (Subject + Modal + Base Verb):
MUST
MIGHT
CAN'T
Scene 2: The Rainy Day Surprise
Evidence Found:
The sky is dark and grey.
People are carrying umbrellas.
No one is wearing sunglasses.
MUST
MIGHT
CAN'T
Scene 3: The Quiet Party
Evidence Found:
Balloons and cake are on the table.
The lights are off.
10 people are hiding behind chairs.
MUST
MIGHT
CAN'T
GRAMMAR FORMULA:
Subject + Modal + Base Verb
Example: "He must be happy." (Not "must is")
Reported Speech Slides Detective Briefing
THE REPORTING WIRE
Lesson 3: Introduction to Reported Speech
Step 1
Hear the Quote
Step 2
Report it back
What did they say?
Direct Quote (Exactly what they said)
"I see the thief!"
Reported Speech (Telling someone else)
She said that she saw the thief.
The Secret Changes
1 Add "said that"
2 Change I to he / she
3 The Verb Time Machine (Backshift!)
THE VERB TIME MACHINE
PRESENT (Now)
IS / AM
ARE
LIKE
BACKSHIFT
PAST (Then)
WAS
WERE
LIKED
TELEPHONE REPORT!
1. The teacher whispers a secret quote to Student A.
2. Student A whispers to Student B.
3. The last student must stand up and say:
"The teacher said that she wanted pizza!"
Mission Check: Ready to Transform?
Witness A says:
"I am scared."
He said that he...
was scared.
Witness B says:
"They have the keys."
She said that they...
had the keys.
Grab your Witness Transformer worksheet!
Witness Transformer Worksheet THE WITNESS TRANSFORMER
Mission 3: Reporting Statements
Security Clearance: Level 4
Agent:
The Reporting Code
Verb Change (Backshift)
Direct Speech Reported Speech am / is was are were have / has had like / want liked / wanted
Pronoun Change
I
He / She
My
His / Her
Witness Statements
Witness A (Man)
"I have the diamond in my pocket."
Report:
He said that he __________________________________________________.
Witness B (Woman)
"The suspect is very tall and wears a red hat."
Report:
She said that the suspect _____________________________________________
Witness C (The Kids)
"We are hungry and we want some pizza."
Report:
They _________________________________________________________________________
Agent Reminder:
Remember to change the PRONOUN (I/My) and the VERB TENSE (Present to Past)!
Interviewing Slides The Detective Times
EXCLUSIVE:
THE TRUTH REVEALED
Lesson 4: Interviewing and Reporting
Press Pass Required
Vol. 4 Issue 1
Becoming a Reporter
Ask Questions
"What is your name?" "Where are you from?"
Take Notes
Write down exactly what they say (Quotes).
Report the News
Use Reported Speech for your final article!
Today's Mission:
Interview your partner about their weekend. Then, write a report using:
"He/She said that..."
"He/She liked..."
Pronoun Shift Review
Witness Says:
"I"
You Write:
He / She
Witness Says:
"My"
You Write:
His / Her
Witness Says:
"Me"
You Write:
Him / Her
Live Interview LIVE 🔴
Celebrity Quote:
"I love my fans and I have a big cat."
Your Newspaper Article:
The celebrity said that she loved her fans and she had a big cat.
Watch the Verb!
Love → Loved
Have → Had
My → Her
Ready to Scoop?
Open your Press Pass Interview Sheet. You have 10 minutes to interview your partner. Ask about their hobbies, family, or pets!
TIMER: 10:00
Press Pass Interview Sheet Press Credentials
OFFICIAL PRESS PASS
Interview Dossier
Capture the Quote. Report the Truth.
Reporter Name:
Witness Source:
1. The Opening Question
Reporter asks: "What is your favorite hobby and why do you like it?"
Direct Quote (Write exactly what they say):
2. The Lifestyle Question
Reporter asks: "What do you usually do on the weekends?"
Direct Quote:
3. The Future Question
Reporter asks: "What do you want to be when you grow up?"
Direct Quote:
Reporter's Quick Check
When you write your final report, remember: "He/She said that..." and Present → Past.
Morning Gazette Template Volume XII ... No. 45 The Morning Gazette Price: Two Cents
Weather: Cloudy with a chance of clues MONDAY, JANUARY 19, 2026 Final Edition
Exclusive Reporter Interview
Headline: (Write a catchy title here)
By:
Reporting from:
Yesterday, I sat down with ____________________________________ to discuss their life and hobbies. When I asked about their favorite activity, they said that _________________________ ____________________________________________________________________________________________________ ____________________________________________________________________________________________________.
Next, we talked about their weekend plans. They reported that _________________________ ____________________________________________________________________________________________________ ____________________________________________________________________________________________________.
Finally, I asked about their future. They said that they wanted _________________________ ____________________________________________________________________________________________________ ____________________________________________________________________________________________________.
Artist's Sketch
A portrait of the witness as described during the interview.
Grammar Patrol
Check your verbs! Did you backshift?
Did You Know?
Reported speech is used by detectives all over the world to share information from witnesses accurately!
Case Dossier Eraser Top Secret
Case File: #772-B
The Case of the
Missing Golden Eraser
Subject: School Property Theft
The Scene of the Crime
At 10:15 AM, the Principal noticed the Golden Eraser was missing from the trophy case. The case was locked, but the key was still in the door. The floor was recently mopped and still wet.
Physical Evidence Collected
👓
Item 01:
A pair of reading glasses found on the floor.
🧼
Item 02:
A small smudge of pink soap on the glass.
🐕
Item 03:
One long brown dog hair near the base.
Witness Statements
Witness: Mr. Clean (Janitor)
"I am in the cafeteria at 10:00 AM. I have my dog with me because he is sick."
Witness: Ms. Read (Librarian)
"I like the Golden Eraser very much. It is beautiful! I want to hold it one day."
Detectives: Analyze the clues and fill out your
Final Investigation Report Worksheet Investigative Report
Official Case Conclusion Form
DUE DATE:
Today
Detective In Charge:
Precinct Number:
1 Reporting the Statements
Rewrite the witness quotes from the dossier using Reported Speech .
Mr. Clean (Janitor):
He said that he _________________________________________________________________
Ms. Read (Librarian):
She said that she ________________________________________________________________
2 Deductions from Clues
Look at the items in the dossier. Formulate three logical deductions using Modals .
MUST
MIGHT
CAN'T
The Verdict
Confidential Conclusion
I believe the culprit must be ____________________________________
BECAUSE:
Mystery Answer Key Teacher Answer Key
The Case of the Missing Golden Eraser
Eyes Only
The Culprit: Ms. Read (The Librarian)
Ms. Read stole the Golden Eraser because of her deep admiration for its beauty. She entered the office, used the key left in the lock, and accidentally dropped her reading glasses during the theft.
Evidence Mapping
The Reading Glasses
Connects directly to Ms. Read. As a librarian, she is the most likely person to wear reading glasses.
The Pink Soap
Evidence that someone washed their hands recently. Ms. Read's statement about wanting to "hold it" suggests she touched it with her hands.
The Red Herring (Distraction)
The Dog Hair: While there is a brown dog hair, Mr. Clean explained in his statement that he had his dog with him in the cafeteria. The hair likely drifted into the hallway or was carried on his shoes, but his statement (Reported Speech practice!) confirms his location was elsewhere.
Grammar Integration Check
Target: Reported Speech
• He said that he was in the cafeteria.
• He said that he had his dog with him.
• She said that she liked the eraser very much.
Target: Modal Verbs
• It must be Ms. Read because of the glasses.
• It might be Mr. Clean, but his dog was sick.
• It can't be a student because the case was locked high up.
