Charter Arms Pathfinder or Taurus M94... two of the least expensive 22 DA revolvers new. I have heard okay things with the Charter Arms and heard so many negative things about the M94 that I wouldn't suggest you try one.
A used H&R DA revolver would be a good choice especially the M999.
I wouldn't suggest you teach kids to shoot with a snubbie revolver. That comes later.
Keep your eyes open and you might find a S&W M63 used in very good shape and that would be a good choice. Of course, the S&W M617 is about the best DA 22 made, but they are expensive as are the M63's new.
I would suggest you get a Ruger Single Six even though it is more expensive than the Heritage Rough Rider (RR). But if it comes down to nothing at all or the Rough Rider, I'd choose the RR.