What should we do about this school situation?

My son is in 2nd grade. He can be difficult & is a challenge. He's not disrespectful to his teacher or mean to other kids, he just has a problem focusing/listening/following directions, it's hard for him to stay on task. At home has has spelling words, it's hard to get him to study, but eventually it happens & he gets 100% on his tests he takes at school. When he brings work home that he does in school, it's all Ds & Fs. I know his teacher is fed up with him, so she just has a whatever attitude instead of working with him. One day he didn't come home w/ his spelling words. His dad went into cl to get them. When he asked the teacher if they had spelling words this week, she said yes, she gave them to my son. His dad said well he never brought them home can I have another list. She said well, I gave it to him. His dad just stood there & said well he doen't have it so I need another one. She said he should have brought it home. His dad just stood there in disbelief. Finally, the teacher hesitantly gave it to him. I just think that is wrong, he's 7 yrs old, why would she almost refuse to give us his words? I just thing that was unacceptable on the teachers part. I feel like she has given up on our son because she's not up for the challenge. He's failing 2nd grade. We're going in to talk to the principal next week. But what should we do? I don't want to anger the teacher, but my son deserves someone who's going to actually teach him. Should we demand a new teacher? Should we have the principal talk to his current teacher & see if she changes her tune? I don't want to feel awkward around her & if my son continues to stay in her cl, I don't want her to give him good grades to p him to get us off her back - I want my son to learn/to earn his grades, but with help. Also, we didn't know there was problems until open house & parent/teacher conferences because she didn't communicate with us. The only thing we knew was that he was getting bad grades. She even said that he is smart when he pays attention. I know my son can be exhausting when it comes to getting him to do work, but I feel it's her job to make sure he gets his in cl work done & learn from it. She subtly suggested that he should be on medication. I don't believe in that, it's unhealthy for the child, & it's an easy way out. The child needs to be worked with/taught, not medicated. We try working w/ him at home as much as we can, but it's not homework he's failing at, it's the in cl work. How would you handle this?