Nearly everything we know is expanded or swollen by heat, and contracted or shrunken by cold. But water is queer. It's ; particles huddle closest together, and fill the smallest amount of space when in a liquid state. And it is expanded by both heat and cold. When heated to the boiling point and turned into vapor it takes up the most space. Steam confined in a boiler bursts iron walls, if it can get out in no other way. So in freezing, water expands to a larger bulk. That is why ice floats in water. If the water happens to freeze in a pipe, where there is no room for it to expand, it bursts the pipe. Some people think the thawing bursts the pipe, but the thawing only shows us the places where the frost burst it. You know a quiet pond freezes more quickly than a running stream. One way to keep your pipes from bursting in zero weather, is to open a faucet a little way. That keeps the water flowing so it is less likely to freeze.