Hand-raising is a quiet gesture and does not disturb other students while they work. It also does not create the chaos that several students simultaneously shouting answers does. When a student raises her hand, the teacher can clearly see which student requires help.
If a teacher is not paying attention, he will not see a raised hand. Engrossed in grading papers or writing at his desk, a teacher can become oblivious to students working quietly. This can especially become a problem if a young student raises her hand because she needs to use the bathroom immediately.
Classes in computer labs may take advantage of messaging programs that students can use to quietly tell teachers they require assistance. The signal might appear as a flashing light on the teacher's computer screen. Facial expressions are other nonverbal cues that signal help is needed. Students might appear confused, frustrated or remain silent instead of verbally confirming, upon being asked, that they understand a concept.
Teachers can ensure successful classroom communication by clearly explaining to students at the beginning of a semester how to quietly signal for attention. Students in kindergarten and first grade may find this concept foreign, so it may take time for students to learn to wait patiently for their turn to talk when the teacher responds to their raised hand.