This activity is great to be used with teens and adults. It's a very good tool for the teacher to evaluate how students perceive their sef-steem. I like to use it as a warm-up but it can be a good wrap-up too.
1) Teacher asks student to say what the most important things in the worldare for them and give one adjective to describe it.
2) Before the class the teacher will have stuck at the bottom of an empty box a mirror. then, in clas, after this brief discussion, every student in turns will be invited to open the box and see his/her reflection. They should also say one adjective to describe them. Before I invite them to start opening the box, I usually say that inside the box there is something very important for me in the world.
3) If you want, as a follow-up, you can have them sitting in pairs to discuss how they felt when they saw their reflection and so on but usually the activity is always very rewarding for both students and teacher.