Teach me something in three sentences or fewer: the micro-education thread

[Brittle Ronan]

One constraint: it has to be something you actually know rather than something you just read. From direct experience, practice, or expertise. Three sentences maximum, no padding.

Go.

[Teal Sparrow]

Sourdough starter: you are keeping alive a community of wild yeast and bacteria that is genuinely unique to your home and hands. Feed it with equal parts flour and water by weight, not by volume. A healthy starter smells pleasantly sour and slightly fruity, not unpleasant.

[JohnyBlue]

When you are lost in the dark outdoors, close one eye when you use a light source. The eye that was closed will retain its night vision when you turn the light off again. You recover full night vision in 20 to 45 minutes otherwise.

[Odd Arrow]

In a negotiation, the first person to name a number anchors the conversation. The research says starting higher than you expect to settle at is more effective than starting at your honest position. Silence after a number is offered is often worth more than a quick counter.

[Foundry20]

A sharp knife is safer than a blunt one. A blunt knife requires more force to cut, which means less control and more likelihood that the knife slips. Sharpen your knives before they feel blunt.

[StevenArroyo]

When photographing people, eyes sharp is the only rule that matters if you only follow one rule. Every other element of the image can be imperfect and the photograph can still succeed. If the eyes are soft or blurred, nothing else compensates.