Tip: Don’t just assume that pairwork is the best option. Consider alternatives.
Background
It’s the cliche of the communicative approach: work with a partner. The idea is that students will get more speaking practice if they work with just one other person (they will speak for 50% of the time) than if they are in a class of ten working as a whole class (they will speak for 10% of the time). There is also the idea that they will speak more freely if not ‘on show’ in front of the whole class. Both ideas are valid, and I guess that in my own teaching (and I should add that I’m talking about small groups here, max 6 people), I ask the students to work in pairs perhaps 40% of the time. Another 20% of the time I ask them to work in threes – I find that three is better than two if the activity is more open-ended and brainstormy. You’ll never get a dead-end where students just stop and look around with three, you might with two.
That leaves approx 40% of the time where I have whole-class discussions. That’s more than when I started teaching. Why did I increase? First because of the tendency for students in pairs to go off at a tangent – I’m not talking about an intersting topic-related tangent, I’m talking about mindless chat (yes, I know that mindless chat is Social English, but you know what I mean – and in a monolingual group this will almost certainly be in L1 anyway). Second, because I find that students often prefer it. The atmosphere is more buzzy, more fun, and it’s interesting to hear what all the other class members have to say. A greater variety of personal backgrounds will bring to the discussion a greater variety of ideas and lexis – and students sense this. If a partner’s language level (or business knowledge) is just a bit below their own, they very quickly sense that the input coming in to them is not going to be very useful.
Very often I combine the different options: a whole-class warmer, and then the group splits into pairs for a more focussed, personalized speaking activity.
And one piece of strong advice that I would give: if you do a lot of pairwork in your classes, regroup the pairs constantly (ask them to sit in a different place next to a different person each time they come into class). There really is nothing worse for a student than to find themselves always doing pairwork with someone who they don’t particularly get along with, who has little in common with them, who has a totally different personality etc. This is reason enough for them to stop coming to your classes.