I'm guessing that is most common in the NE United States and in the northern tier. That is like the Canadian system, by the way, where 3yo children are routinely placed in "JK," classes, meaning "junior kindergarten, year one." Those kids are not really 'accelerated' at all, but that would reflect an ambiguity in the way the question is asked. It's the rough equivalent of "preschool" here in most of the United States.


Schrödinger's cat walks into a bar. And doesn't.