Counterproductive teacher-student interactions: how to help?

Mom of a 14-year old with an IEP for ADHD, here. My kid has a B in a class, but the teacher has been very dissatisfied with her attitude and behavior, even though she has not historically had disciplinary problems. She struggles with work pacing and transitions, which really seems to bother him, as he has told her it’s disrespectful. He chastises her publicly up to 3x per class, in front of her peers. When she laughed nervously after being called out once again, he viewed that as further disrespect. My kid says teacher gets visibly angry - red faced and shaking, sometimes. This has been going on since the start of school this year, but teacher has never made a referral or contacted me about it. My husband and I are scheduling a call with teacher to discuss, but do you have any tips for how I can be constructive? I admit I’m a little angry and kind of creeped out, so I know I need to do some reframing of my own thoughts, first.