These warmers all use questions as a starting point to the lesson.
Teacher to student
Ask individual students questions about the topic at the beginning of the class. Allow for spontaneous, real communication to develop. Questions on the topic of education could be: Did you like school when you were a child? Why or why not? What was your favourite subject? Who was your favourite teacher?
Student to student
Instead of you asking the questions to the students, write them on the board and tell students to ask and answer the questions to each other. Make sure you also write on the board that they must do this in English. This gets the class all talking from the very beginning of the lesson.
Student to teacher
Give students a task to find some information out from you. They are allowed to ask you ten questions to find the answer. Tell them you can only answer 'yes' or 'no'. A task like this on the topic of school and education might be Find out what I studied at university, or Find out what I was like as a student.