What does it mean to understand?

The essence of understanding in science is often, um, misunderstood.

The “scientifically literate” supposedly can rattle off lots of facts: the boiling point of water is 212 degrees F, hurricanes are caused by evaporation and condensation of ocean water, fog is a cloud on the ground, the cold you feel when you get out of the shower is caused by evaporation.

All facts, stated simply and separately. Any one might appear in question form on a standardized test, with the correct answer hidden among three “distractors.” If you get three of four, you’re literate. Only two, you fail the test. If you get all four, you’re a genius.

But the facts miss the important idea. If science is just a bunch of descriptive facts, then we haven’t learned a thing. Surely true understanding is about the connecting ideas between the facts. Yes, water boils at 212 degrees F, but even below this temperature there are bits of water (“molecules” if you want to get fancy) that enter the air as water vapor. Yes, fog is a cloud on the ground, caused by water vapor re-condensing when the temperature is too low for those molecules to stay in the gaseous state.

Hurricanes happen when water vapor condenses, releasing the very heat it took to evaporate it in the first place. That heat powers the hurricane, driving 100+ mph winds. You get cold when you step out of the shower for exactly the opposite reason. Evaporation is a cooling process. As the most energetic molecules escape from the water drops clinging to your skin, the average temperature of what remains drops lower. The powerful and deadly hurricane and your shivering reach for the bath towel have something deep and profound in common. And that is understanding.