Ruby (In the Forest of the Night)
Ruby was a student at Coal Hill School and a member of the Coal Hill Year 8 Gifted and Talented Group. Ruby demonstrated a knack for noting the obvious, such as identifying the "X" in a sum in its location on the class white board, rather than solving the equation for her maths teacher, Danny Pink. During a museum sleep over, Ruby took note of a peculiar red ring on a section of a tree on display. When the Doctor revealed that the trees were in fact protecting the Earth from the solar flare, instead of witnessing the event, the Gifted and Talented Group left the TARDIS because they missed their families.
Ruby believed she lacked an imagination simply due to Clara saying so, but actually had quite a vivid one. She appeared to miss the point of questions as, stated above, it took Danny three tries to make her understand the Maths questions. (TV: In the Forest of the Night)