Five Children and It (book + audio)

Five Children and It is a children's novel by Edith Nesbit, first published in 1902; it was expanded from a series of stories published in the Strand Magazine in 1900 under the general title The Psammead, or the Gifts. It is the first of a trilogyLike Nesbit's Railway Children, the story begins when a group of children move from London to the countryside of Kent. While playing in a gravel pit soon after the move, they uncover a rather grumpy, ugly and occasionally malevolent sand-fairy known as the Psammead who is compelled to grant one wish of theirs per day.

The children's wishes are:
Chapter I: To be as beautiful as the day. Because the servants then do not recognize them and shut them out of the house, subsequent wishes are all with the proviso that the house servants should not be able to perceive the results of the wish.