Hi Chokosaki
One of the points I make in my activities book for teens and adult learners is to put the onus on them some of the time. For example I use several activities in class that the students prepare instead of me.
That has two main benefits: if the students are picking the topic or producing the work then they are more involved in it, and thus more motivated during the lesson to see how what they prepared turns out.
They do the prep work not me!
So let me give you some concrete examples. In all cases first you demo the activity in class with an example prepared by you so that every one understands the task and knows what they are expected to prepare.
Decisions:
These are mini-role-plays. Some may be very quick, some may take longer so you need plenty of scenarios so that you don't have to attempt to drag something out artificially.
Give students a scenario and ask them what they would do. Student A has to then persuade the others to come around to his way of thinking. If another student disagrees he has to say why. Student A earns points for each student who shares his opinion. In the next scenario it's student B's turn to persuade the others to share his view.
The issues can be big or small, such as for the weather, you have planned a walk with a picnic but it's raining. Do you go anyway? Or, there's a drought, but your neighbour is watering his lawn every day, at five o'clock when it's still hot. Do you say/do anything? If you are wondering what scenarios would be interesting to your students you'll find out if you let them come up with them themselves!
Call my bluff definitions:
This activity is useful because it can be tailored to fit any topic. It's a good way for the students to revise vocabulary that has come up during a unit and deepen their knowledge of the words. It can also be really fun depending on the definitions that come up.
Students prepare three definitions of a word that they look up in the dictionary, two true and one fake, or one true and two fake. The other students listen to the definitions and decide which the true one is.
The advantage of activities like the two above is that they fit into any unit, and students prepare the activity for you. There are plenty of activities like this one here:
Call my bluff teaching idioms
Some ideas for conversation questions here:
ESL Conversation activities for teens and adults
All the best
Shelley