Sciencespeaking topic
Why a nettle stings and then fades: its needle-like hairs inject histamine and acid, and your reaction is a response to a chemical defense. How does a plant make a 'needle'?
— nettle trichome chemistry
practice with this topic
Set the timer (5-30 min), take 20 seconds of prep if you like, start talking. Jot your thoughts onto the sticky-note board.
similar topics
- When your body sweats it stops overheating, and when you're cold it shivers to warm up; like a thermostat it always returns to balance. But this very urge to return to balance sometimes works against you in addiction and obesity. Why does the mechanism that keeps you alive also trap you?
- Some life experiences, like famine or trauma, can change the 'on/off' setting of genes without changing the DNA itself, and that setting can pass to the next generation. So a famine your ancestor lived through may have left a mark in your body. Is memory stored only in the brain?
- Simpson's paradox: a trend that holds in every subgroup can reverse when the groups are combined. How can the same data say both A is better and B is better?
- The number of bacteria living in your gut is greater than the number of human cells in your body. So most of what you call 'me' is not actually you. When you make a decision, are you really 'yourself,' or a coalition in which the microbes inside you are lobbying?
- A moisturizer doesn't add moisture to the skin, it stops moisture from escaping: humectants pull water from the air but in a dry environment can do the opposite and dry the skin out. Is glycerin our friend or our enemy?