We've explained to our pupils customs linked to this day allover the world, and especially in Spain.
In France, we use to eat a special cake called "Galette des rois".
Something is hidden inside ( it used to be a bean ).
The yougest one goes under the table and decides who will receive each part.
If you get the bean in your part, you are king of the day, and you can choose a queen ( or you are queen and you can choose a king ).