Plates at our planet's surface move because of the intense heat in the Earth's core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again.
Why does the tectonic plates move?
The plates can be thought of like pieces of a cracked shell that rest on the hot, molten rock of Earth's mantle and fit snugly against one another. The heat from radioactive processes within the planet's interior causes the plates to move, sometimes toward and sometimes away from each other.
How do plate tectonic plates move?
Plate tectonics move because they are carried along by convection currents in the upper mantle of the planet (the mantle is a slowly flowing layer of rock just below Earth's crust). Hot rock just below the surface rises and when it cools and gets heavy, it sinks again.