First of all when a child is crying I believe that they are doing the best they can to help themselves. Most likely it has worked for them in some way or another to cry - they get what they want, they make someone uncomfortable, they change the situation in some way. Therefore they are doing what they think is best. Also, crying can be very organizing to an overstimulated body. If they have had a lot of stimulus (such as a new person in their space) crying is a way to help themselves cope.
Second, I believe that the best way that I can help a child is to remain comfortable myself and help them find a more effective way to help themselves. I see crying as an opportunity to help these children learn faster than I did growing up, that unhappiness is not a very effective tool. It would be much more useful to simply tell people what they would like or choose something else to do if their first choice is not possible. The easiest way to do this is to remain calm and comfortable myself.
I then explain to the child that I don't know what they want when they cry, but they could just tell me or even show me. I slowly offer them things they might want (slowly so as not to make it seem as if crying gets them things faster). If they continue to cry like my children did last week (they both talked of wanting out). I explain the whole situation of why we are there and where there parents are and anything I can think to explain. If they still cry I then explain that it is their playroom and they are free to do what they like in it, if they want to cry they can. However, I like to have fun when I'm in the playroom. I then take my energy off the child and go play by myself making sure to have fun (I like to even hum or sing to myself to really completely take my energy off of them). Sure enough, both children wanted to eventually play instead of cry.
The more comfortable and consistent we can be with this the faster we are going to teach our children that crying doesn't work!!!! Therefore let's all see crying as a wonderful opportunity to teach our children that it is way more fun to be happy!
wishing you all a week of happiness!
(side note: last weekend the girl cried 45 minutes in my 1st session, 5 minutes in my 2nd session, and none in my 3rd and 4th - the comfortableness and consistency paid off!)