Let's face it, time-out doesn 't always work.
Got any fresh ideas for stubborn, smart, grade-schoolers that actually work? Aside from duck taping her mouth shut, I'm plum out of ideas (yes, I'm kidding, but it's tempting, isn't it).

OMG it is very tempting some days. I have a 9 yr old in 3rd grade and the only thing that works is taking away her privilages, no tv no playing outside (although i find this actually punishes her dad and I instead) I also make her write sentences explaining what she is in trouble for and how she can fix it. This works amazingly well with her becuz i put it up on the fridge for a few days and everytime i start getting that adorable little attitude i refer her to what she has written asking her if she wants to rewrite it. Which she never does. Time out is a joke but standing in the corner reciting her spelling words for the week or her times tables outloud works and she is studying at the same time. I also when she gets pretty much at my breaking point inform her that I NEED A TIME OUT and go in my room and forbid her from bothering me ( i get 30 mins in time out cuz im 30) it is amazing ho wmuch better you can approach a situation when you cool off like that. When i come out of my time out i ask her if she knows why i went to time out. Most of the time she does, when she doesn't i tell her the reason (example being she has been being very rude all day or talking back etc).
PS I do not help eher with the spelling on the writing becuz it is in her words. I dont care if it is spelled right as long as she knows what it says. As someone else stated I do not reward her daily for good behavior I do however have a point system. For example 50=ice cream treat. But she earns points vs allowance and she can loose them for bad behavior the only way she can earn them is by doing her daily chores.. she gets 5 pts a day for taking out the trash each chore has a point value. 1 point a day for keeping up with her room. Just remembered this and thought i would add it.