Inside the Factory: Pencils

Gregg Wallace visits a German pencil factory, learning that the main material in a pencil is not lead but graphite. Cherry Healey examines the properties of graphite, discovering that if a single layer is stripped of atoms from its surface, a new material known as graphene is made. Thin and virtually invisible, embedding this in phone screens might mean that in future they can be rolled up. Historian Ruth Goodman finds documents that show the death of handwriting has been prematurely announced on many occasions, dating right back to the invention of the printing press