Another vote for a DA S&W or Ruger revolver in .38/357. Just can't go wrong. Though a Glock is a very solid runner up fitting the stated requirements, as they just don't stop either. And frankly, I've had more issues with my S&Ws than my Glocks (but the S&Ws are still my first pick).
On further review it would be much easier to teach a newbie how to make 25-yard hits with the Glock trigger than a double-action revolver trigger. Flipped to the other side of the coin, with the single-action capability of a S&W or Ruger you could teach a new shooter to make 50-yard hits more easily than with the Glock.
NRA Master, Highpower Rifle, Across-the-Course
NRA Expert, Highpower Rifle, Mid-Range Prone