Floating and sinking
Chemistry · Early Years · The School
Guess first, then test
Before you drop anything in the water, SAY what you think will happen. Guessing first is what makes it an experiment. Without a guess it is just playing. Get a cork. A coin. A stick. A stone. A plastic lid. Say your guess for each one, or write it down. Then try them.
Big things can float
Here is the surprise. A tiny coin sinks. An enormous log floats. So it is not about how big something is. Ask what else might matter. What is it made of? Is it hollow inside? A closed plastic bottle floats. Fill it with water and it sinks.
Boats
Metal sinks. But a metal ship floats. That is because a ship is a shell with air inside it. Try it with foil. Screw some foil into a ball and it sinks. Shape the same foil into a little boat and it floats. Same material. Same amount. Different shape.
Take a big empty plastic bottle. Put the lid on. Put it in a bowl of water. It floats. And it is the biggest thing on the table. Now drop in a small metal spoon. It sinks straight away. Now fill the bottle with water and put the lid back on. Predict what will happen. Then try it. It sinks. The bottle is the same size it always was. So size cannot be what decides. What changed was what was inside it.