Time: 10 to 20 minutes.
This is a good way to review vocabulary and create some healthy competition in your classes. All you need is a list of vocabulary the students have been studying; or, even if you want to introduce a new topic, words that they should know can also be used. You can use this game in classes with four to about fourteen students (more than this number is not feasible for the amount of time required).
Choose a number of words that you want the class to revise (e.g. gerunds). Divide the class in half and have the two groups select a name for their team; write the names on the board. Place a chair for each group in front of the board facing the class (so that students sitting on them will have their backs to the board). To start the game, ask one student from each team to be a volunteer and have him/her to sit in the "hot seat" in front of his/her team. Next, write one of the words on the board and have the students try to elicit the word from their teammate (who is not allowed to turn around to see the word on the board). They can mime (my favourite) or explain the words (using English), but they cannot write, spell or do anything else that might be considered cheating (if students get truly stuck on a word, I tell them the first letter – in rare cases, even the second letter). Whichever student in the "hot seat" guesses the word first earns a point for his/her team. Repeat the activity with the other words, choosing a different student (to sit in the chair) each time.
For intermediate and advanced levels, sentences, and not only words, can be used. The student in the "hot seat" must say the exact sentence that is behind him/her.
This game can really cause some excitement, so make sure you won't be disturbing other classes being held near yours. As an added incentive, I sometimes bring in chocolate candies to give to students when they discover 'their' word/sentence really fast.