As a postscript to the blog about this:
I'll ask you to look at the way Oswald left the lunch room. He left by going through the office area where he encountered Mrs. Reed. She spoke to him, and he did not respond. And then he kept going. He didn't turn around and head back into the lunch room. He went out the same way he came in, through the office area and using the front stairs. That was his route, coming and going. Even in the Ruby and Oswald movie, they showed him doing that.
It's one thing they got right.