Tess calls the sloped side of the bathtub (opposite the faucet) the "slide." When bathing, Tess likes to run her bath toys/animals down the slide and say "whee!", as though she were riding the slides at the park herself.

So tonight during bathtime, Tess starts asking me about how plumbing works. We talk about water under pressure in pipes, about faucets and valves, and we apply this understanding to the bathtub faucet and then the sink. Next she queries me about the toilet plumbing and starts me on a familiar recitation of the grand adventure the poop and pee take from flush to sewage treatment plant.

She asks about the relative sizes of the pipes as sewage moves from house to neighborhood to main to plant. Upon learning the pipes get bigger and bigger, she smiles and looks aside--wheels obviously turning.

She then looks up at me and says something like, "Maybe the poop and the pee will have fun going down their own slides!"