Here is a collection of activities, some of which I have chosen from Dave’s ESL Café, and added variations to the examples of how to cope with a large group activity.
In your first encounter with your group of students, you need an icebreaker. A good way to start is to make meeting each other into a game. This will put everyone at ease immediately.
Introduce yourself to the students, and instead of the usual drill of having each student say his name and something about himself, which not everyone would remember anyway, tell students to imagine that they are at a cocktail party. So immediately you get them up and moving instead of them sitting tense and anxious about this new language. They will now play the 3 question game. Before they start moving around, have each of them prepare 3 questions to ask other members of the group. For example “Have you ever traveled to another country before this country?" or “Where is the most interesting place you have ever traveled"?
Give them time to mingle and ask at least three people in the group one of the three questions they have prepared. Then after they settle back into their seats, have each person stand and give his or her name. After each student does this, have members of the group tell what they know about this person based on the answers they have given to the questions they were asked.
Nationality finding. Give each student or whisper in each student’s ear the name of a country. Then have them mingle with each other and ask what country each person is from until they find their partner or partners depending on how large the group is. They must do so first asking as an adjective (the nationality), and either responding with an adjective or a noun. For example student A asks student B “Are you French"? Student B replies “No, I am Belgian" or I am from Belgium" or if he finds his partner or partners it could be “Are you Puerto Rican"? “Yes, I am Puerto Rican" or “Yes, I am from Puerto Rico."
“We are the World." Have your students represent the world according to their own nationality. You stand in the middle and say “I am the school." Ask students to stand on the field in the country or the city where they were born. If the student was born in a city close to the location of the school, they should stand close to you, if not they should stand far away. After they figure out the relative locations of their countries, you can then yell for example, “Where is Peru’? or “Where is Ethiopia’? and “Where is Colombia"? They can respond by a show of hands. They can place themselves North, East, South or West of you. This will allow them to do a bit of geography in the language and have fun at the same time.
The concept behind these activities is really to avoid a common trend among students to team up with other students who speak their native language or are from the same geographical region. Choosing an esl group activity from one of these for each lesson will break them out of that tendency and motivate them to speak the target language of English.