I was recently asked how to change screens working directory. It took me a few minutes to realize the benefit of this as I typically have different screen sessions for different purposes. But after thinking about it for a few minutes I have been in situations where what I was doing in a screen session morphed and it would have been nice for new windows to be opened to a different working directory than where I started my session.
A few minutes of grepping around in man -a screen gave the answer.
C-a:chdir /path/to/new/dir