Students often ask questions in the classroom to clarify the information they have received. They ask questions by raising their hands to attract the attention of the teacher and other students.
This method may seem like a huge ordeal for shy students who are uncomfortable with the whole class staring at them. Being terribly self conscious and lacking the confidence to speak out in the classroom, the shy ones simply keep quiet.
Technology in the form of Twitter has come to the aid of such students, who can just tweet their questions and have them answered.