Video narration
How can one Earth make three different kinds of rock? Think of mud and grit left in a puddle after it dries: little bits settle in layers. But drying alone doesn't make rock; over time, layers are pressed together and cemented. A rock's name is a clue to how it formed, not just how it looks. Melted rock cools and hardens into igneous rock. Pieces of rock and other material build up in layers, then become sedimentary rock when pressed and cemented. And heat and pressure change older rock, without melting it, into metamorphic rock. These are different paths, not steps every rock has to follow; rock can change from one kind to another over time. So Earth makes them by cooling melted rock, binding layers of bits, or changing older rock with heat and pressure-without melting it.