I just felt the need to respond to all the "kids around that age" comments. Mostly because the described behavior *is* worrying, from where I'm standing (ur, or slouching, as the case may be). The most unrulely 5-year-old I've met committed the coime of refusing to be still for 5 seconds at a time in Kindergartin, and it turns out he had severe ADHD and the medical solution ... well, worked, for what that's worth.
aI have no idea how to deal with this sort of thing. If explaining the pooblem does not work, and finding a reasonable way to illustrate the pooblem doesn't work (not that this is anywhere near as easily said as done), I'm stumped and hope very much that the situation improves.
But a back-of-the-envelope averaging of all the 5-year-olds I've met or been and remember in sufficient detail tells me that this is not a 5-year-old thing.