There are at least ten books in the series. Titles include Millie Goes to School (the first), Millie of Lowood House, Millie Plays the Game, Millie's Finest Hour, Millie in the Upper Fourth (the fifth), and Head Girl Millie.
The jacket copy describes them as "moral and uplifting". Girls wallow in them, while their brothers consider the things to be slush.
In real life, Lowood was the name of the boarding school endured by the young protagonist of Charlotte Bronte's famous novel Jane Eyre.