What is diffusion?

Diffusion is when things move from where they are more concentrated to where they are less concentrated, like sharing toys so everyone has a fair number.

Imagine you have two jars: one full of red marbles and the other empty. If you pour them together, the red marbles will spread out until both jars have about the same number. That’s diffusion in action, the marbles moving from where they are more concentrated (the full jar) to where they are less concentrated (the empty one).

Think of a bottle of soda. When you open it, the fizzy bubbles go up and out because the carbon dioxide inside is more concentrated than outside. It moves from the bottle, where it's more crowded, to the air, where it’s less crowded.

Or picture a kettle on the stove. The hot water rises, and the cold water sinks in, mixing together until everything is warm. That’s diffusion too, the heat moving from where it’s warmer to where it’s cooler.

Diffusion helps things mix and move around in our everyday world, just like marbles, soda, or kettle water.