Look at a smoke grain under a microscope and it jitters along a jagged, random path. The grain is far too big to move on its own. It is being knocked about by countless tiny, fast, invisible air molecules striking it unevenly from all sides. Hide the molecules and the grain still dances, which is the evidence that matter is made of moving particles.
MissionWatch the grain wander, then explain why it moves.Streak 0Best 0
The smoke grain jiggles because:
large grainsmoke particle
small dotsfast air molecules
heating the air speeds the molecules, so the grain jiggles more vigorously.