I am sick of going to lectures which start with the speaker bouncing in and telling us they really want their session to be interactive. This is normally followed by them turning down the lights (which you shouldn't do) and proceeding to bore me with dull slides. After 20 minutes they will complain that 'no-one's asking questions' and then go back to droning on. At the end they ask if anyone has any questions, and are surprised that nobody cares and just wants to go home.
This doesn't need to be you. Follow these steps to make your sessions more interactive:
1) Don't talk about how interactive you're going to be
Because of people like our hero above, people switch off when you tell them they're going to have to speak to each other, or you. Saying your talk is going to be interactive is like saying your talk is the funniest thing your audience will hear for the next six months. Let them decide how interactive or funny you are.
2) Get the audience talking early
Once people start talking, they're more likely to engage. For any audience bigger than about 5 people, you can use 'Buzz groups' (I've used this for groups of over 300 - it's challenging but it can work well). Ask a question that people can discuss for a couple of minutes, then give people an opportunity to feed back to the wider group. For example, if the talk is about why teapot design is important, our boring hero would just start with a picture from Wikipedia of a teapot and start droning. You could ask everyone to discuss in twos or threes why they think teapot design is important. When you think about it, it kind of is.
This works because people have an opinion but don't want to look like idiots in front of the group. By sharing what they think in a group of two or three, they have already tested their ideas out to the people next to them. As they (hopefully) have not been immediately socially ostracized, they are now far less reluctant to say something to the bigger group.
3) Pause after you ask a question
It can take a long time for people to answer a question, especially if you ask a large audience. Ask your question, and then stand there. Don't move. Feel how uncomfortable the mood gets. Asking a question of an audience is a game of chicken. Sometimes it takes 30 seconds for someone to pipe up, and believe me that feels like an eternity when you're up there at the front on your own.
This is something to balance. If you introduce yourself and then, completely cold, ask a big audience a question in the hope someone shouts out an answer, you're asking a lot of them. You may get someone keen who responds but you may also get a lot of awkward fidgeting. Once people have started talking to each other, the mood warms up and you can get people speaking to you directly.
Most people wait less than two seconds after asking a question in a lecture, before going on to answer it themselves. This isn't a wild-west duel. Give people time to think.
4) Don't make questions you ask too taxing
If you ask a big audience a complex question, you can wait there all day and people won't answer. Anything you ask early on has the primary aim of getting people comfortable talking. Once they feel safe you can add to the complexity, but interactivity requires people to trust you're not going to make a fool of them.
5) Never ever make someone feel awkward for answering or asking a question
Sometimes people say silly things. No matter how great you think you are, sometimes you do as well. If someone has plucked up the courage to say something in front of the audience, never make them regret it. They, and everyone else, will stop interacting with you completely.
6) Leave enough time
If you think you're going to get people to engage with a question and discuss effectively it in 30 seconds, you're almost certainly wrong. This is especially true early on in the session, when people are still getting used to the idea of talking to each other and you. Leave enough time for people to consider a question, discuss it amongst themselves, and come to some sort of consensus as to what the answer might be. This could be 5 or 10 minutes, or even more. If this means you have less time to go through your slides, that's great. They were probably less interesting than the stuff your audience was talking about. Cut some of your slides out, you've probably got too many anyway.
7) Listen for the dip
If you've asked a room of 50 people to talk about a topic, the volume starts low. Then, as they get warmed up, the volume increases - this is where they are talking about your subject. After a while, the volume dips again. This is where they've exhausted the discussion about your question. Then the volume goes up again. This is where they've moved on and are talking about what they got up to at the weekend. Listen carefully for when the volume in the room dips, and use this moment to get the attention of your audience and start collecting their thoughts.
There are loads of other ways to make sessions interactive - people can write stuff on post-its and stick them on a board for discussion. They can feed back with software that lets them answer question on their phone, with the results displayed on the projector. They can ask questions through twitter, or via email or SMS, for them to be answered by the presenter. This only scratches the surface of the ways to interact with audiences.
In the end though, being interactive involves your audience talking more and you talking less. When they do talk, you can listen, and consider what they say, and be open to how that fits into your presentation.
Not all sessions have to be interactive, but people tend to remember things better and feel more engaged if they've contributed in some way. Making sessions more interactive usually makes sessions better.