Mikey has been interested in fluid dynamics for a long time. I remember when he was just turning one year old a friend asking what was his favorite bath toy. My reply was, "a cup." Mikey is three and a half now and I didn't think there was any more fluid dynamics that he could really learn. Last night he proved me wrong. The bubble bath bottle was empty and it was unlike any other container he had every had in the tub. The bottle was clear and it had a long neck. When Mikey put it under water he heard the glug glug glug of the water filling and watched big bubbles float up to the bath water surface. Then he showed me the best part of his discovery - not only did the vessel fill differently than a cup, it poured differently, too. The water glug glug glugged out as Mikey watched the large air bubbles explode inside the bottle.
Here is a link to a bubble bath that has a bottle similar to the one in my story. (But it is glass...)