I would move away from the specific moments, and look at a larger context that may be leading to him feeling disempowered. That's a primary key to cyclic bullying, abuse, violence.

There are many ways a bright kid can feel disempowered in a pre-school... such as pedantic baby talk from adults, interacting with age peers who are hardly distinguishable from the toddlers, being presented with instruction they already know and understand can make them feel stupid rather than smart, teachers verbatim repeating themselves to deliver a point, having younger kids get much more respect and attention, etc.

But, the particular mechanic he responds with has to be addressed, violence begets violence.