Ot en Sien (Ot and Sien) are two little children who appear in a series of stories which were written in the Dutch language more than a hundred years ago. Ot (short for “Otto”) is a little boy and Sien (pronounced like the English word “seen”), whose name may be short for “Francine”, is the little girl who lives next door. Although they are now very old-fashioned, the books are still popular in Holland. They were written in rhyme and were illustrated with colourful pictures.