Hi,
There's no doubt that teaching is a challenging job, and some classes are more challenging than others. I think Till had an excellent idea for your daughter to tap for herself first to relieve the stress and frustration. For example, "Even though this class is driving me crazy, I'm still a great teacher." Whatever her emotions are, she can tap on them to relieve her own emotional stress.
Second, I think your daughter is on the right track in keeping them busy, but I would encourage her to create some fun, challenging projects or centers in the room that they can work on only when they are through with their regular work. She might talk to other teachers of gifted children to get some ideas.
If she isn't using a behavior folder that goes home daily to parents, she might consider that, as well. With second graders, a happy face/sad face folder is easy or a number system: 3 is great, 2 is ok, 1 means they didn't meet the classroom behavior expectations.
Since I am not familiar with her situation, I don't know if your daughter is familiar with EFT and/or if it is possible for her to do tapping in the classroom or not. It can be presented as a game -- "we are going to tap out anything that might keep us from learning today." Let the children offer ideas. They may come up with such things as, "I want to be home," "I don't like this class," "I want to play," "I don't want to work," etc. Just don't take what they say personally, don't be offended or hurt, and don't tell them they "shouldn't feel that way." The children generally love to do the tapping. If you have a TappyBear in the classroom, that's great, too. Sometimes as a special treat, students may get to hold the bear.
I hope some of this helps!
Hugs and Blessings,
Syandra