I use 'Find Someone Who' as a warm up or as an activity following a lesson on verb 'to be' with adult learners. The reason I specify 'adult learners' is that the questions relate to adult situations. The activity consists of finding people in the class who answer the given characteristics (e.g. find someone who is friendly / who is a construction worker). All the questions are built with verb 'to be'. There are 20 questions divided on two pages, so each half of the class has one page. Not only does this activity help with 'to be' questions, it creates a dynamic environment because students walk around the class and get to know each other.