I can understand why you’re having difficulties. One of the most difficult aspects of working with teenagers is getting them to speak. Many teachers have a tendency to treat teens as adults but this is usually a mistake. They don’t have the same life experiences and knowledge of the world. They are often shy and don’t like expressing opinions that are different to the opinions of their peers. This makes discussions and debates difficult. It’s also quite common for a new teacher to do a lot of the talking. You might feel nervous and compensate for your well-planned lesson by talking. After giving instructions, allow yourself a period of silence. You’ll probably find that the students start talking; you might also see them looking confused, in which case you can give them some assistance.
The ideas you have tried would probably work well when the group is more used to your way of working. Improvisations and role plays involve drama. I have always found that drama works better when a class is used to working with the teacher and they work well together already. Also if they only have basic English abilities, they aren’t ready to be creative yet.
Speaking activities work better if you give students time to prepare. Give them plenty of time to absorb and practise the language, prepare what they’ll say and get together their ideas. Speaking spontaneously is actually a very difficult task when you think about everything involved: ideas, grammar, vocabulary, pronunciation…. So do a lot of controlled practice first. They will need a lot of spoon-feeding at the beginning but will gain more confidence and perform better with time.
Start by working on what they enjoy. If they want to talk about video games, they could do a questionnaire abut which games they like. They could prepare the questionnaire in groups and then ask their classmates their questions. Questions can involve: which game do you prefer xxxx or yyyy? Which is the best game you have? Which is the best game you have ever played? How many games do you have? This is an example of controlled practice.
Remember speaking can also involve very simple activities: after doing a grammar exercise in writing, students can repeat the same orally in pairs. They just need opportunities to get their mouths around the language. It doesn’t always have to be fun and novel. A lot of the speaking we do in everyday is not fun or novel!
An activity that I have found always works with teens is “am I lying”? Put them in groups; give a few pictures to each group. One student takes a picture and, without showing it to his classmates, describes it to the others. He can describe what is really in the picture or lie about what he sees. The others have to guess whether it is true or not. Give them the language they need to do this, and remember to include you’re lying, cheat, etc.
You can also look at answers I gave on November 16, 2004 (about teaching teens) and on 16 March 2005 about getting students to speak.
Please write in again, if you'd like more ideas.