Pencil A pencil was a device used to write found on Earth . An HB pencil was made from graphite . Another type of pencil was 4H . Certain pencils , known as " coloured pencil s " , came in many colour s , including blue , green and red . The ends of certain pencils featured rubber s , or erasers , which could be used to erase graphite marks made . ( TV : " Fear Her " , " The Runaway Bride " ) People bit pencils when they were nervous . ( PROSE : " Totem " ) Pencils were maintained by sharpening them , which could be done mechanically , or manually through the use of knives as did Mary Shelley . ( TV : " The Ribos Operation " , AUDIO : " The Silver Turk " ) The Doctor , in many of his incarnations , demanded a pencil to help him think . ( TV : " The Time Meddler " , " The Ice Warriors " , " The Dæmons " , " The Talons of Weng - Chiang " , et al . ) Artists would draw using pencils . For example , a Parisian artist once sketch ed Romana II with one in 1979 . ( TV : " City of Death " ) Child ren , inexperienced at drawing , would often draw with coloured pencil s , mess up , and then scribble on the drawing to cover up their mistake . ( TV : " Fear Her " ) Time Lord s also used pencils for drawing , just as Susan had used one to draw a flower . ( TV : " The Dead Planet " ) Pencils were also used for writing . For example , Marco Polo would use a pencil to transcribe his adventures in his journal . ( TV : " Marco Polo " ) Graphon Narmolis , a shape - changing criminal , once assumed the identity of a coloured pencil , and was used by Janie , a school girl , to write her homework . ( COMIC : " Pencil Pusher " ) A man living on Arcadia who was dying from cancer wrote his memoirs using burnt sticks for pencils and old sheets for parchment . ( PROSE : " Prelude Deceit " ) Pencils were naturally used in school s such as Coal Hill School , both in class and for homework . ( TV : " An Unearthly Child " , COMIC : " Pencil Pusher " ) Pencils had other uses as well , such as the basic function of a stick . The Tenth Doctor once used one to extract a sample from a Vespiform sting , and Agatha Christie had earlier used the same pencil as a pointer . ( TV : " The Unicorn and the Wasp " ) When , in 2012 London , the Isolus took over Chloe Webber , a lonely child , Chloe began drawing people and objects — snatching them from space - time , and sucking them into her paper . She did this under the influence of the Isolus , who was lonely as well , trapped away from her family of around four billion . Not only could Chloe suck living organisms into drawings , but she could also " create " organisms " from " drawings , as she did with the scribble creature , a creature made entirely from graphite , and her father . The Isolus , with Chloe unconscious , showed a skill of pencil drawing quite capably and quite quickly . Trish Webber , her mother , would hide her pencils , but she kept a secret stash in a doll . The Isolus was eventually freed when the Tenth Doctor and Rose Tyler found its spaceship , and Chloe was no longer capable of extracting life through drawing . ( TV : " Fear Her " ) The Tenth Doctor once used a pencil to demonstrate how the Huon particles in the heart of the TARDIS were attracted to the identical particles in Donna Noble , using a mug to represent the TARDIS . When Donna , shocked , questioned , " I ' m a pencil inside a mug ? " the Doctor joked , " Yes , you are . 4H — sums you up . " ( TV : " The Runaway Bride " ) The Third Doctor once demonstrated a " conjuring trick " to Dr Tyler involving making a pencil " disappear " and a flower appear in its place . ( TV : " The Three Doctors " ) A young Clara Oswald , who later became a companion of the Eleventh Doctor , had a " best pencil " , which she unfortunately lost . ( WC : " " ) A young Amelia Pond , another future Eleventh Doctor companion , thanked Santa Claus on Easter 1996 " for the doll s and pencils and the fish . " ( TV : " The Eleventh Hour " )