Float or sink?

In your book, Our Wondrous World (Chapter 7), Meera and Dhruv drop different things into a bucket of water. Before each one goes in, they guess: will it float or sink? You can write 'F' for things that float and 'S' for things that sink.

Some results are what you might expect. A heavy iron nail sinks, and a light leaf floats. So you might think: heavy things sink and light things float.

But it is not always so! An empty steel bowl (katori) is much heavier than an iron nail, yet when it is placed gently on the water, it floats. And some light things sink: a small coin is light, but it goes straight to the bottom. Your book says that whether a thing floats or sinks cannot be decided just by whether it is heavy or light. Other things matter too.

Here are some clear results. A leaf, a cork, a piece of thermocol and an ice cube float. An iron nail, a stone, a marble and a coin sink.