Really liked this article as it is a problem all chicken owners should know how to handle.
I would explain what a "crop" is and how a chicken processes food by allowing the first stomach (the crop) to pass food to the second stomach (the gizzard).
I would add that this can be a physical blockage that can lead to death by dehydration or starvation if left untreated.
I like the list of things that could cause Sour Crop. The only thing I don't agree with was not giving the chicken water for 24 hours.....that's a long time.
It actually is the only way for massaging it every hour to work. I agree, but I did a lot of research and it said not to worry about your chicken getting thirsty.