Naughts and Crosses by Arthur Thomas Quiller-Couch, Fiction, Action & Adventure

One day, when she and her boy were out playing, the boy stopped for a moment. He stood and smiled at her with the sun at his back -- and his shadow lay upon the whitened steps. But the silhouette was not that of a little breeched boy at all, but of a little girl in petticoats -- with long curls, where the charwoman's son was close-cropped!
"The Magic Shadow" is one of the dozen-plus stories of everyday life -- and of not-so-everyday delight and wonder -- in Naughts and Crosses, by the author of The Splendid Spur.