Respect can be defined in multiple ways. I believe that is not only words that one says, but most importantly the actions that a person takes and demonstrates towards themselves and others.
This can be demonstrated im many different ways in the classroom. First of all, the teacher needs to show respect to all students and themself. This can be done by showing no partiallity towards one or groups of individuals in the class. This also can be a very simple "hello" or a smile.
I think that respect is a similar concept to trust. I feel that just like trust, respect takes time to build up and just one minor slip-up to break it down. Respect is not something that is just given to someone, a teacher needs to earn it by giving it. A student will not be respectful to the teacher if the teacher is not respectful to the student and likewise. This concept of earning respect is a crucial and critical aspect to the tone and level of eargerness to learn of the classroom. The teacher needs to demonstrate and explain the importance of respect in order for the students to follow suit.