Stuck? No problem!

With all the hustle bustle preparing for her Easter celebration, Marash Girl found herself with two glass bowls, bowls exactly the same size, one stuck inside the other.  No problem.  She knew exactly what to do to separate them.  Do you?

Marash Boy, observing the problem, was in a quandary.  "How are you going to separate them," he asked Marash Girl.  

"Oh, simple.  When I was a kid" Marash Girl replied, "we used to stack glasses of the same size, two at a time, into each other on the shelves in order to make space, as we had little shelf room in our kitchen.  (Not that we have any shelf room in our kitchen today, she noted.)  That would often leave us with one glass stuck inside the other.  When we expressed concern, my mother would laugh and simply put cold water with ice inside the topmost glass, and set the bottom glass in hot water.  Soon enough we could separate the two glasses.  Cold contracts, heat expands, right?  Didn't you ever do that when you were a kid in your house?"

With a wry smile, science whiz Marash Boy commented, "Our glasses never got stuck."