second graders!
I have been teaching second grade for a lot of years, and it's been awhile since I've had a group quite like the ones you've described! This year all 5 sections of our second grade have the same problem, very unsettled, not quite ready to get with the program, think they can do pretty much what they want, when they want, etc. As a group they are very immature. But we watched them in first grade and knew we were getting a handful. Every day seems like the first day of school! They just don't seem to "get it!"
As for advice.... Well, what we all do is clamp down on them. By that I mean, you stick to a routine as much as possible, you keep reinforcing the rules, reteaching them if necessary, and don't put up with their nonsense. If they go down the hall noisily, we go back and try it again, if it's one or two, then they have to go back to the room and give me some of their time from PE, recess, whatever... Usually by now I can ease up on them a little, but with this group they're still learning the hard way. Hopefully, they'll figure it out before the end of the year!!
Good luck! I don't know if I helped any, but you're not alone! Just be firm!!!
