The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun. The deepest layer is a solid iron ball ...

Seismic waves are shock waves that propagate through Earth's layers after an earthquake or explosive event, traveling at different speeds depending on the density and state of the material.

You'll see how warm and cold water interact and learn about density currents that occur in oceans and atmosphere ... Notice how the demonstrator uses a simple drinking straw to create distinct layers, ...