This activity can be used either as a warmer or as a practice activity for forming yes/no questions, and/or reported questions, and/or narrative tenses. It is suitable for group classes at elementary level upwards.
Start by telling one student (let’s call her Carla) that you and the rest of the class are going to invent a dream that she had last night, and then when she comes back, she will ask some yes/no questions to find out what her dream was. (You could subsitute “dream” for “something that happened to you yesterday” if more appopriate in your teaching context.)
Tell Carla that she must leave the room while the rest of the class invent the dream.
When Carla has left the room, tell the rest of the class that in fact you’re not going to invent a dream at all. Instead, the answers you give to Carla’s questions will depend entirely on the question itself. If the last letter of the last word of the question is between A and M, then the answer is yes. If the last letter is between N and Z, then the answer is no. (You could change this for the last letter being a vowel or a consonant, or anything else you can come up with).
Now, chat amongst yourselves for 5 minutes to create the illusion of the discussion time required to invent all the details of Carla’s dream, and then invite her back into the room and have her sit in the middle of the circle, or at the front of the class.
Remind Carla that you have invented the dream she had last night, and that she must now ask a series of yes/no questions to find out what her dream was. As she asks the questions, she is under the illusion that the class has gone into a lot of detail thinking about her dream, whereas in reality of course she is creating her own dream based on the questions she asks.
You can go on as long as you like, depending on whether you’re using this as a warmer or as a practice activity.
If you’re using it as a practice activity for questions, Carla of course gets the practice when she asks the questions. For the rest of the class you could have the students try to remember and write down or tell you orally all the questions that Carla asked.
For reported questions, have the other students report to you what Carla asked (“She asked if…”) either as you go along or at the end of the activity.
For narrative tenses, you can stop at various points as you go along and have either Carla or another student recap the dream so far. At the end, you could develop this into a writing activity, having pairs or small groups discuss to reconstruct the dream. At lower levels you could restrict this to past simple, and at higher levels include other narrative tenses – past continuous and past perfect.
The only slight drawback to this activity is that when you’ve done it once, the game is up with that group – you won’t be able to fool another student!