Using past modals for speculation and deduction: 3 activities

In this post, I am describing 3 activities where students practice using past modal verbs for speculation and deduction. I have been using them with upper-intermediate, advanced, FCE, and CAE students who often struggle with the concept of using modal verbs for something other than expressing ability or obligation.

#1 Speculation: Photographs

Some historical pictures started showing up on my Twitter feed and it gave me the idea of using them with my learners. This was the first photo I showed my students asking them to speculate about what might have been happening at the moment the photograph was taken (stressing the fact it happened in 1939 i.e. the past).

We worked on determining the levels of certainty considering the following:

  • When was the picture taken?
  • Why was the man doing what he was doing?
  • What was he feeling?

Examples of sentences my students came up with:

  • It must have happened during the war.
  • The soldiers must have been thirsty.
  • The soldier in the picture must have had a good sense of balance.
  • The soldier in the picture might have wanted to help his comrades.
  • The soldier in the picture might have received an order to bring tea.
  • It might have been a bet.
  • It might have been a prank.
  • The soldier might have felt amused / nervous.


Another old photographs that have worked well in my classes are old pictures of famous people. I have been using them to revise personality adjectives and past modals. This is one of my favourite photos (source) . The first challenge that piques students’ interest is figuring out the name of the famous person (usually accompanied by “No way! Is this really him/her?!”).

Students look at the picture and speculate about the person’s in question life or personality at the moment the picture was taken. Their only clues are the photo itself and the caption (which I reveal later or not at all). Again, we first tried to determine how certain we were about his personality (generalisations/ oversimplifications allowed!), what he felt / thought when the photo was being taken, what attitude towards life he might have had as a young man.

Here is what my students thought of Bill Gates:

  • He must have smoked a lot of marijuana when he was young.
  • He must have been a relaxed young man.
  • He might have been high when he was arrested.
  • He can’t have expected to become rich one day.
  • He might have got an idea for Microsoft after his arrest because he got scared.
  • He can’t  have taken this arrest seriously.

I wrote more about using pictures for practising past modals here and here.

#2 Deduction: Crime Scene Investigation

Variant A

This activity is usually lots of fun and enables you to engage the whole group into the creation process. Here is what you need:

  • a setting (a living room, a classroom, an office etc. confined spaces usually work best)
  • a character (who sadly gets murdered in the first scene)
  • a set of clues (written words of pictures) that might be either completely random or somehow connected.

The aim of the game is to recreate the events leading to the main character’s death. Analysing clues that gradually appear during the investigation, students invent what must / might / can’t have happened at the crime scene before they arrived.

Here is a Google presentation I have been using with my students. After each clue appears, they have to produce a conclusion.

Clue #1: You look around the office, terrified. Suddenly, you notice a cigarette butt on the floor!

What is your conclusion? 

Anna might have been a smoker.  / The killer might have been a smoker. / The killer must have smoked after killing Anna.

Deducing who the killer was is not really the objective here but the students often get very engaged and invent very convincing storylines.

Variant B

If you like improvising and work with like-minded students, you might make them responsible for the story:

without informing them where the game is going (don’t mention the murder yet) ask your students to come up with:

  • a place
  • a person
  • 10 random objects

Then, explain that the person has been found dead in the place and  10 random objects have been spotted at the crime scene. Ask your students to deduce what each object had to do with the crime using past modals. You might work together or divide your students into pairs/groups. Make sure to provide some relevant examples of the target language.

#3 Speculation: Impossible Situations

The aim of this activity is for the students to react to a prompt describing an impossible/unlikely encounter or event.

Prepare a list of impossible situations and cut it up. Students draw a piece of paper from the stack and need to react to the prompt using past modal verbs to speculate about the reasons/explanation for the situation.


Your most punctual colleague came to work late every day last week. –> He might have made some new friends / He might have become a father  /  He might have partied every night / He can’t have set his alarm clock etc.

Encourage your students to invent as many explanations for each situation as possible.


  1. Thanks a lot! I’ve just come by this great website! Terrific work! Hope to use it in my classes:)

    • Great news! I’d love to find out how these ideas worked out in practice for you 🙂

  2. Just writing to say that your posts are truly amazing! What a great job’s done! Millions of thanks!

    • That’s great to hear, thanks a lot for taking the time to comment!

  3. Hi there???? I used these lessons & exercises for my own students. They’re great????????

    • Hi Sarah, go ahead. This is a free edu resource for EFL/ESL teachers to use in their lesson. I hope your students like it!

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