One of the side pleasures of moviegoing is watching an actor literally grow up, especially when he keeps playing the same role. Zachary Gordon has a third go-round as perpetually aggrieved, bewildered, adorable dork Greg Heffley, and two years after the first installment of this most likable of the current franchises, Zach looks older and has if anything gotten even more natural. Not a hint of precocity in him. And while the part is broader, Robert Capron as best friend Rowley continues to light up the room (even if the “room” is a blindingly sunny outdoor scene) with his sheer good feelings. In fact, the movie is perfectly cast, its legion of returning characters all welcome. There’s an Afterschool Special-ish sub-plot involving Greg’s relationship with his dad that might be annoying if Steve Zahn weren’t playing Dad. (Doesn’t this fine actor get better offers?) But mostly, KID is as carefree as the summer vacation that frames it. — Jeff Schultz