I find this is crucial in establishing a 'fair' relationship with them. I've seen many teachers who concentrate their eye contacts on only a few students, and this does affect the feeling in a group. I've also trained myself to make positive comments, and to be as direct as possible. I say 'Good' instead of 'That's enough'. I've actually heard teachers say 'Well, let's see who fails at this one', when introducing an exercise.
Some teachers get reassurance when their students fail.
We must all have encountered the teacher who gives a self-satisfied smile when a student makes a mistake. If you are confident in yourself as a teacher and in what you are teaching then the students will trust you. So that the students follow what they are doing. Student's Individual Sense of Belonging to a Group 1.