Sociology is the study of the social relationships of people and organizations. Teachers and students do not function in a vacuum, but in the social relationships of their milieu. Therefore, sociology is of profound importance to a teacher. First, a good teacher needs to understand how his or her own students' sociological backgrounds have an impact on their educational experience, second, the teacher needs to attend to the sociology of the classroom as an organizational entity, and third, the teacher is empowered by having insight into the sociological environment of the school and the school district.
Students come from a variety of sociological backgrounds, and in order to connect and engage with each student, the teacher must have some understanding of those backgrounds. This enables the teacher to best tailor learning to meet each student's particular needs. A student from an impoverished home and a student from a wealthy home are likely to have significant differences, for example. A student from an impoverished home might have some serious learning deficits and need more time and care, while a student from a wealthy home might very well need greater challenges than the regular curriculum. (I realize this sounds off-putting, but the statistics bear it out.) Students who are from different cultures might have a hard time acclimating to the dominant culture in the classroom, and students from different races often have different ways of showing respect, for example, having been taught it is rude to make direct eye contact with those in authority. A teacher who has no knowledge or insight into sociology is not going to be able to do a very good job of understanding or engaging any student.
In order to create a classroom community, the teacher has to have some understanding of sociology. How the students coalesce as a group or do not coalesce as a group is to a large degree a function of the classroom as a sociological organism. The teacher with some awareness can arrange for groups or pairings that will enable students to forge connections. The teacher can inculcate an environment of respect for differences, be they cultural, religious, ethnic, or racial by modeling his or her respect for all differences. Some understanding of sociology helps the teacher to see what might be going wrong in the classroom, as students do not behave properly or do not get along, for example.
The teacher is also functioning in a sociological organization, the school and the entire school district. The culture of the school and/or the district has a great bearing upon the teaching environment. The teacher needs to understand the efficacy and the shortcomings of the bureaucracy. The teacher needs to understand where power lies in the organization, in order to navigate through the system effectively. This kind of understanding may prove to be the difference between getting or not getting additional resources for the students. The teacher needs to understand how the school district fits into the social makeup of the community. Parents may be active participants in school matters or be completely content to leave it all up to the schools. The culture of the district can thus have a large effect up the everyday life of the teacher and the teacher's effectiveness in the classroom.
On three different levels, the individual, the classroom, and the community, a good working knowledge of sociology makes for a better teacher. I took sociology as an undergraduate, over 40 years ago, and the principles I learned then I still find valuable, in teaching and in life in general.