We're going to have a chat about locking doors

When I started to put Kalena down for her nap this afternoon I discovered that her door was locked.  From the inside.  And the room was empty.  Apparently she locked the door, came out of the room and pulled the door shut.  This doorknob?  Has a KEY lock.  To which I have no key.  I tried the old bobby pin trick, even though that's mostly good for push locks.  After I broke the bobby pin in the lock I considered taking the doorknob off, which is when I discovered there are no screws on the outside.  Luckily I remembered a trick I used a time or two in college and finally managed to get the door open using an outdated plastic insurance card.  If she keeps this up I'm going to get really good at breaking and entering.