The teacher is afraid of my nephew

My nephew started his first ever year of school two weeks ago. As the title suggests, he's having a hard time adjusting. I'm going to try my best to be as unbiased in my re-telling of what's been going on as possible, because I really would like advice.My sister grew up being afraid of her guardians growing up, mainly because they would often go above and beyond with their punishment. From the stories she's told me (I won't specify since it's not my story to tell), it sounded like downright abuse to me. When she had her own kids she tried to be the opposite of this, and it didn't really help. Both of her children are actually not that bad on their own. Her daughter is 13 and is as annoying as teenagers can be. She also has ADHD, so we're dealing with that. But apart from that? She's not a loose cannon or anything. The hardest thing is getting her to wash her dishes. Her mom has never forced her to do anything, so it's hard getting her to feel obligated.My nephew pretty much does what he wants, which more often than not is sitting down with his tablet and playing games. He's 5 and suprisingly calm for his age. He's also very big. People think he's 7/8. Regardless of his size or strength, he doesn't like to trouble people and doesn't want people to trouble him. Which, of course, is not conducive to a first week at kindergarten.When the teacher asks him to do things, he is defiant. At first, he'll just say no, but if you push, he tends to act out. In this case, he tore one of her shapes (these brightly colored shapes that had been stapled to the wall) down. While he was angry, the teacher gave him this coloring page to work on (as punishment, I guess? I'm not entirely sure) and he tore that up, too and handed it back to her. At the end of the day, the class has this tradition of giving the teacher a high five before meeting their parents. He doesn't give her a high five, and in her words, "slithers" past her to meet the person picking him up (me).She had a meeting with his mother and told her, very straightforward-like, that she was afraid of my nephew. She brought in a separate teacher to deal with him on his own.Now, for my question. Regardless of my personal perspective on how he's been acting, two things need to be solved:I need to find a way to help him adjust to being at school and to following someone else's directions. Like I said, he's naturally a very calm and (when he wants to be) obedient child. I know I'm his aunt so my opinion on this might come off extremely biased, but he really is. But, again, he's not used to being obedient when he doesn't feel like it. His mom's off-hand approach has not really prepared him for this area.I know from experience (as a "difficult" kid myself) that if a child is treated differently, they will act accordingly. How can I offset the potential self-esteem/social/other issues that can arise from him being separated from the other kids?I've been really distraught over this. I'm 19 years old and have no experience parenting. My sister is at a loss. She doesn't want to make her children feel afraid the way she did, and I understand that, but she also doesn't want her son acting up in class.Please help. via /r/Parenting http://ift.tt/2bo6jul