My five-year-old started asking some weird questions over dinner the other day about the insides of erasers. My initial answer ("pink rubber stuff") clearly failed to satisfy him, however, and he started to talk about the "balls and sticks" he’d seen in a cartoon, where the characters had "zoomed" inside a big pink eraser.

Realizing that the cartoon must have been representing molecules, I happily launched into a basic discussion of atomic theory, using Lego blocks in what was surely a deft and transparent analogy. Each block represented an atom, a few blocks together comprised a molecule, and with enough molecules, one builds anything! He listened with interest; neither his eyes nor his demeanor flagged and wandered, common enough with kids his age..

Silently congratulating myself for being clever enough to not only identify his question, but also explain it so neatly and hold his interest in the bargain, I wrapped up my little lecture, anticipating that little glint in his eyes that he gets when he’s just learned something new. I sat back and took a sip of water, waiting for said glint to appear. Instead, he hauled his bare foot up onto the dinner table (provoking an outcry from my wife and a laugh from our two-year-old) and, giggling, asked me to smell it.

Humbled by a five-year-old. AGAIN.