how would you show the particulate nature of matter?

Particle nature means that matter is made up of particles. It is not continuous.

We can explain the particle nature of matter by the follwing experiment:

If we take a crystal of potassium permanganate and add it in one litre of water. After sometime the crystal divides and colour the whole water becomes pink. So we can conclude that there must be a large number of particles in a crystal of potassium permanganate which divide themselves when added to water . 

On further dilution, the colour of portassium permanganate solution will become light. And ultimately a stage is reached when the particles cannot divide further into smaller particles.