Actively choosing to disobey equals a time out here. I don't give time outs for ANYTHING else, as I view them as pretty ineffective for anything else, but for this it has worked well for me. It usually only happens a few times tops. For particularly stubborn children, less than 10 times. It's pretty boring to sit in the kitchen until you feel ready to listen and then still having to go and do what you were originally asked/told to do in the first place.
I would tell her, "Oh dear. When you choose to ignore Ms. Teacher then you have to sit in the kitchen. Please let me know when you're ready to listen." She will throw a whopper of a tantrum the first few times, if she's a stubborn little one. When she slows down to a whimper is when I would ask her, "Are you ready to listen?" Usually, they'll wind back up again. But, eventually life goes on and they figure out that they either listen or they get to sit.
I have 12 children. If I'm actually asking/telling them to do something then I
need them to do it. They can take a minute to process, but ultimately it needs to be done. We work on good manners ("Yes ma'am!") and having a cheerful attitude here as well (not pouting, not saying, "Oh maaaan!"). We have a lot of group discussions about these things, I praise those that have good manners and a good attitude, I model it all myself for them, etc. Obviously, ignoring me doesn't mesh well with any of that.