The three rock types are introduced. Granite is named as an example of igneous rock. Igneous rock can be formed underground from molten rock, or magma. It cools slowly, resulting in large grained rock. Igneous rock can also be formed above ground from lava. It cools quickly, resulting in small grained rock.
Students could use this clip as a revision exercise in modelling the rock cycle. This could then be extended to look at the uses of rock related to the properties.