Cameron Diaz has been in a lot of films I wouldn't consider worthwhile, to the point where I’m not really a fan anymore (try watching "The Other Woman" and then try to find something good about it – you won’t). Here, though, she finds a genuinely funny part and commits fully. Elizabeth Halsey (Cameron Diaz) is a teacher who plans to leave her middle school after a year to marry Mark (Nat Faxon). After being dumped…