Effective teachers focus constantly on community building because it generates better learning experiences and outcomes.  Strong communities are built by consistent student investment, student empowerment, and a personalized learning environment.  A sense of community in your classroom will also allow your students to overcome mistakes and difficult days, build relationships with you and others in the classroom, and develop confidence in who they are as an individual.  "Community building" can't just be another educational cliche.  Effective teachers know it is a key to success.