I think there is a very subtle difference. hand and hand just refers to two hands not necessarily together.hand in hand implies that the hands are connected or together.
Teachers like to know that students are attentive and taking in the material presented in class. Raising your hand to answer makes you an active participant in the learning process. It shows that...
because some people dont like being touched its best if you feel anxious around people its better to use your strategies like touch myself instead of putting my hands on someone else