Exasperation!

While my students are 'angels' compared to last year, I still am struggling against the beast known as chatter in my classroom, especially during last period. I've tried: lunch detentions, calling parents, sending students to a 'buddy' or 'time out' room, and moving seats. Yet these children still love to talk!! Talking is not the worst thing in the world; however, I want my students to respect themselves and their teacher enough to not talk during direct instruction. Is this just how 6th graders are (please tell me no)? Perhaps it's the time of year? Or maybe its my hormones (a pregnant woman and 6th graders don't mix well at times)?