Sunday school

 was an informal form of schooling that took place on Sundays. (TV: The Evil of the Daleks, PROSE: The Eleventh Tiger) Sunday school was the only form of education Gwyneth received. (TV: The Unquiet Dead)

When Clara Oswald was young, she attended Sunday school with "a nice lady teacher" in a small church room that smelt of oak polish and had felt-tip colouring on the walls. (PROSE: Into the Nowhere)