Sophie didn't know the incantation for the carving spell. She didn't really like Ancient Runes, and therefore hadn't really read anything about it before coming to school. Add in the fact that her mother hated the subject, too, and that amounted to this class being Sophie's very first experience with runes.

So instead, she took out her color changing quill.

She set to work doing a rainbow drawing of six different Algiz shapes. If she couldn't give the incantation to carve the shapes, then she could at least do a really pretty drawing. ...and so were the thoughts of an eleven-year-old girl.