Class Behavior While I Was Absent

I was notified by several teachers and students not in my classes that my students had a particularly difficult time maintaining proper standards of behavior while I was absent on Friday. Aside from the hassle of dealing with the aftermath of any substitute, as well as the stress of family-related circumstances which required my absence, I am extremely disappointed in my students in this matter.
While any student may feel a sense of freedom or relief from the regular routine of the classroom teacher, this does not in any way excuse inappropriate behavior on the part of students. More than one teacher told me that students were so noisy while being let out for passing period (a break which I generally do not give my students) that those teachers were forced to stop their instruction to allow the clamor to diminish to a clatter before they could begin teaching again. Additionally, a number of people informed me that several of you were harassing others for perceived unfairness. This behavior will not be tolerated because I know that you are capable of better.
As my students, you represent me and my academic and behavior standards. When you demonstrate that you are not able to conduct yourselves in a proper manner, you embarrass me if colleagues and supervisors notice this lapse.
As a result of this situation, consequences will be swift and severe. Effective immediately will be a seating change, and students will be under strict monitor for infractions of the Classroom, Team, and School rules of conduct.