A single cup of frozen water and a coin can protect your family from invisible danger. By freezing the water first and then placing the coin on top, you create a simple “memory” of any thawing that happens while you’re away. If the power goes out and the freezer warms, the ice melts and the coin sinks. When everything refreezes, that coin tells you the truth your food can’t: whether it stayed safely frozen, partially thawed, or completely warmed.
Seeing the coin still on top means your food never left the safe zone. Finding it halfway down is a warning to be cautious and inspect each item. A coin at the bottom is your clear signal to let it all go, no matter how “fine” it looks. This tiny, low-tech test costs almost nothing, takes minutes to set up, and can spare you from a painfully expensive — or dangerously sickening — mistake.
