I have a 10,7 and 4 yo. As you will notice, most of my advice starts with the obvious - make sure the child is rested and by all means get the child preschool screened to rule out need for,say, Occupational Therapy help (e.g., self-soothing strategies).
Beyond that what's specific to a 2 y.o. is inability to talk well. Secondly, at that age, they certainly can't use "I feel" statements we use in conflict management as adults. So what's left? No tools, no abilities, so total frustration.
You're a teacher so you've probably read a lot about validation. I've read that for 2-5 y.o. you have to say things like "Gee, I can see you're really sad/mad/upset with Joey. [that's validation] What could we do instead of hit/scream/bite to tell him that?" Then with a 2 y.o. you might have to fill in the blank yourself and say "We could say, 'it was actually my turn to ...'"
BTW - the next thing he'll have to learn is how patiently to be "next" for a turn. (All in due time...)
I don't think it's a confidence problem (aren't kids still quite self-absorbed at 2?)-- he just doesn't know what to do when things don't go as planned. He doesn't "have the words" for the situation.
If you walk him through this (like above) for a few weeks, he'll get the thought process/pattern and it will begin to become second nature. Also, put him in preschool so he gets more practice (with preschool teachers facilitating the process and observing his progress). Good luck!