Lesson overview:
A pair of ballet shoes, size 37. A university library card. Half a cheese sandwich, still fresh. A birthday card that says Happy 21st, Zoe! and a phone with 34 missed calls from Mum. This is Bag 0417, left on the last train from Brighton, and students have to work out whose it is. That's what modals of deduction are for: saying how sure you are, based on evidence. In the detective's notebook, students match each conclusion to the item that proves it and decide how certain they can be. She must be a student (the library card). She might be a dancer (shoes can be a present). She can't be a child (she's 21). A certainty dial shows the three zones at a glance, and a short list covers the traps: the opposite of must here is can't, not mustn't; must be + -ing for what is happening now; might not against couldn't. The exercises move from paraphrasing to telling rules from deductions, explaining odd situations, job riddles, two flatmates who hear a noise at 2 a.m. and a second bag where each modal is used once. Students finish by inventing their own mystery bag.
Add it to a class plan and keep track of what you've taught.
