Mineral or chemical sunscreen? Zinc oxide and titanium dioxide physically reflect light, while chemical filters absorb it and convert it to heat. Which is the right choice for your skin and for the ocean, and why?

— sunscreen chemistry, mineral vs chemical UV filters

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

Willpower or environment for building habits? Willpower runs out, but redesigning your surroundings (putting the chocolate out of sight) changes behavior for good. Why is forcing yourself the weakest strategy?
The number zero went uninvented for thousands of years; the Romans built an empire but had no symbol for writing 'nothing.' Writing nothingness down as a thing turned out to be one of humanity's hardest ideas. Why was naming something that does not exist so difficult, and how did civilizations that never managed it still thrive?
Coffee was the Islamic world's secret until it was smuggled out of Yemen; when it reached Europe some wanted it banned as 'the devil's drink,' but the Pope tasted it and gave his blessing. Coffeehouses became the birthplace of revolutions, newspapers, and stock exchanges. Can a beverage speed up history simply by bringing people together?
The plantations built for sugarcane were the engine of the largest slave trade in history; millions of people were shipped across the ocean for a sweet crystal. The white stuff we stir into our tea fed one of the most bitter chapters of human history. How do the most innocent pleasures hide the darkest pasts?
A smell encountered for the first time is never forgotten; smell is the only sense wired directly into the brain's memory and emotion centers, older even than sight. The scent of a spice can teleport you thirty years back in a single second. Why is it a smell, and not an image, that punches through time like this?