Formulate a procedure for beginning the class after the final bell has rung. Require, perhaps, that the students be seated and silent before instruction begins, or that they take out relevant course materials, such as textbooks. Do not begin class before your conditions have been met, in order to firmly establish the procedure. Don't be afraid to deduct points from students who hold up the class or otherwise single them out for reprimand.
As any eighth-grade teacher knows, dealing with unwanted chatting and lack of focus is a year-long struggle. Begin your class off on the right foot by establishing firm rules for inappropriate talking. Think of a sound, like a hand clap or a chime, that will signal your students to fall silent, and discipline students who talk after the sound is given. Try to walk the balance between firmness and patience when running your classroom; eighth graders are bound to talk, but they should be stopped when their talking interrupts learning.
Expect your students to discuss any planned absences with you. Extended absences can set a student behind, so make sure to provide coursework or reading assignments to students who are planning to miss several school days. Establishing clear rules for entering late is important for teachers who want an effective classroom. Mark tardy students on your attendance role, and inform your class that multiple tardies will result in a point deduction on their final grade.
Establish clear rules for eating and drinking in your classroom during the first school day. Most teachers, especially middle school teachers, prefer that food and drink is put away the moment class begins. Consider allowing bottled water, which won't create messes and limits trips to the drinking fountain. If you allow eating, make sure the students understand that messes will not be tolerated, and excessive mess will revoke food privileges for the entire class.
Teachers in eighth-grade classrooms will become frustrated if their students routinely abuse bathroom privileges. Only allow one student at a time to take a bathroom pass, or make one female and one male pass available. Remind your students that the bathroom should be used during passing period. Only sign hall passes for legitimate purposes, and make students wait until you aren't busy teaching to ask to leave the room.