> ## Content Index > Fetch the complete content index at: https://www.lessonpills.com/llms.txt > Use this file to discover other available public pages before exploring further. # Solving mysteries: making deductions about the past - URL: https://www.lessonpills.com/deductions-past-must-have-cant-have/ - Published: 2026-06-30T05:49:58.000Z - Updated: 2026-07-13T05:45:07.000Z - Description: Solving mysteries — a B2 English lesson. Practise making deductions about past events using 'must have' and 'can't have' and expand vocabulary around investigation. - Author: Lessonpills - Tags: B1, Grammar, Vocabulary, Practical English, Audio, Premium, Hedging and speculation ## Summary This 90-minute ESL lesson for **B2** learners explores **Solving mysteries: making deductions about the past** through a real audio recording. Across 11 interactive exercises, you'll develop listening comprehension, vocabulary, grammar, practical communication, speaking skills — all built around authentic English content. **What you'll practise:** - **5 key vocabulary items** with definitions and usage notes - Grammar focus: **Modals of deduction for past events** with examples and practice - Real-world phrases for **figuring out a work problem** - Gap-fill and cloze exercises to test vocabulary in context - Matching exercise to connect terms with their meanings - Error correction to sharpen grammar awareness - A reading passage to practise newly learned language [![CTA Image](https://www.lessonpills.com/content/images/2026/07/icon128-2.png)](https://learn.lessonpills.com/deductions-past-must-have-cant-have?ref=lessonpills.com) Ready to practise? This interactive lesson includes vocabulary, grammar, and comprehension exercises — all based on real English content. [Start the lesson ](https://learn.lessonpills.com/deductions-past-must-have-cant-have?ref=lessonpills.com) Your browser does not support the audio element. ## Lesson activities (11 exercises) Each exercise builds on the previous one. Work through them in order for the best learning experience. 1. **Warm-up** — Discussion questions to activate what you already know about the topic. 2. **Comprehension** — Answer questions to check your understanding of the main ideas and supporting details. 3. **Vocabulary** — Learn key words and expressions from the audio recording, with definitions and usage notes. 4. **Matching** — Connect words, phrases, or concepts to their correct counterparts. 5. **Grammar** — Study **Modals of deduction for past events** — explanation, examples, and key rules. 6. **Error correction** — Find and fix the mistake in each sentence — a great grammar workout. 7. **Practical English** — Learn phrases for **figuring out a work problem** — ready to use in real conversations. 8. **Fill the gaps** — Complete sentences with the correct vocabulary. Drag and drop or type your answers. 9. **Reading** — Read a short passage on the topic and answer comprehension questions. 10. **Discussion** — Reflect on the topic and share your opinions using the language you've learned. ## Vocabulary This lesson introduces **5 key terms** drawn directly from the audio recording: - **To piece together the evidence** — to gradually understand a situation by collecting and combining different pieces of information. - **A red herring** — a clue or piece of information that is misleading or distracting from the real issue. - **To rule out (a possibility/a suspect)** — to eliminate something as a possibility or decide that someone is not responsible. - **An inside job** — a crime, especially a theft, committed by someone with internal knowledge, like an employee or resident. - **To have a hunch** — to have a feeling or guess based on intuition rather than facts or proof. ## Grammar This lesson focuses on **Modals of deduction for past events**. We use modal verbs like 'must have', 'can't have', and 'might have' followed by a past participle to make logical guesses about past events. When investigating a mystery or discussing a past situation, these verbs help us express how certain we are about our conclusions based on the available evidence. **Examples from the lesson:** - *The lights in the house are off and the car is gone. They must have left for their holiday already.* — Use 'must have + past participle' when you are almost certain something happened based on strong evidence. - *He was seen in London at noon. He can't have committed the crime in Paris at one o'clock.* — Use 'can't have' or 'couldn't have + past participle' to express that you believe something was impossible. - *The detective found a footprint in the garden. The culprit might have escaped through the back window.* — Use 'might have', 'could have', or 'may have + past participle' to suggest a possibility when you are not sure. **Key rules:** - Structure: modal (must/can't/might) + have + past participle. - These modals express degrees of certainty about the past, not obligation or ability. - Common mistake: avoid using 'mustn't have' for deduction. The correct negative form is 'can't have' or 'couldn't have'. ## Practical English **figuring out a work problem** In a professional setting, you often need to discuss why something went wrong. These phrases will help you speculate about the causes of a problem, propose theories, and discuss evidence with your colleagues. **Phrases you'll learn:** - **"I'm trying to get to the bottom of why..."** — to introduce the problem you are investigating. - **"All the signs point to..."** — to present a conclusion that seems very likely based on the evidence. - **"I'm wondering if..."** — to gently propose a possible explanation. - **"That would explain why..."** — to show that a theory logically explains another known fact. - **"I'm not so sure that's the case, because..."** — to politely disagree with someone's deduction. [![CTA Image](https://www.lessonpills.com/content/images/2026/07/icon128-2.png)](https://learn.lessonpills.com/deductions-past-must-have-cant-have?ref=lessonpills.com) Ready to practise? This interactive lesson includes vocabulary, grammar, and comprehension exercises — all based on real English content. [Start the lesson ](https://learn.lessonpills.com/deductions-past-must-have-cant-have?ref=lessonpills.com)