Diffusion and OsmosisParticles on the move

MoE-aligned sample unit for interactive practice (curriculumresources.edu.gh themes).

Diffusion is the net movement of particles from a region of higher concentration to lower concentration, until they are more evenly spread.

Guiding question: Why can you smell perfume across a room even if nobody fans the air?

A simple mental model

Imagine dropping ink into still water. At first the colour is strong in one place. Over time particles spread so the colour looks more even. That spreading is diffusion.