2 year old behavior. normal? not?

our son started a new classroom at his daycare last week, transitioning from a 1-2 year old room to a 2-3 year old room. this week the teacher has told my husband that his behavior is problematic. she's particularly concerned that he screams "no" to her and yesterday hit another teacher. she said when they talk to him about his behavior "it doesn't seem to register and he doesn't look at me."they've consulted his previous teacher who said she never experienced these problems. his last class was quite structured and the teacher was older and seemed really capable and in control. this new teacher is younger and i'm not sure how much experience she has.i tried to probe whether, in her experience, this was anomalous for the age group and for a child in transition. after the litany of his behavior problems, she ends with "well, he's 2, and yesterday was a violent day for all the kids." she said she didn't want me to think it's too unusual. but "i've never had a kid yell no at me before."he often yells "no" to me at home, and goes through phases where he hits me and occasionally my husband. we don't tolerate it and use time-out. at the end he always answers why he was in time-out "hit kitty", "throw toy", "pull mama's hair" etc. my impression from reddit and other sources is...he's 2. he's challenging the rules and getting more independent and he's a physical kid.he's super verbal and affectionate and has more compliant days and some more defiant days. i personally wouldn't worry about behavior problems because he doesn't seem at all disconnected to me. but i get that his defiance and the hitting is frustrating. we are dealing with it too.any experiences to be shared would be helpful. we're not sure whether some serious intervention is necessary or whether the teacher is unfamiliar with rowdy toddlers? via /r/Parenting http://ift.tt/2c0SeW6