Video narration
Why does ice melt in a warm drink instead of the drink spontaneously making the ice colder? Heat moves from the warmer drink into the colder ice. The drink cools a little; the ice warms and melts, spreading its water molecules through the drink. The key isn't that the ice gets messier. The drink and ice together can end up in more possible arrangements of their molecules. That's entropy: how many microscopic arrangements fit what you see overall. A clear drink isn't automatically lower entropy than a messy one; visible mess is a poor guide. The cup isn't isolated; the surroundings count too. For a full isolated system-the drink, ice, and surroundings-spontaneous change tends toward more possible arrangements overall. So why does the ice melt? Heat flows from drink to ice, and the combined system has higher entropy.