Step 1 : Introduction to the question "On what day does France observe "poissons d’avril?""
...April 1st is a popular day for celebrating spring by playing practical jokes on unsuspecting family and friends. In France, this day also goes by the name "poissons d’avril," meaning April Fish. To celebrate the day, people try to secretly attach paper fish to the backs of friends, family and colleagues. The "victim" is, of course, unsuspecting. Historians believe the celebrating of April 1st began with the Hilaria Festivals. These were a time of celebration of the Vernal Equinox in Rome. Others believe the tradition began with Chaucer's "Canterbury Tales" in 1392. Source: HolidaysCalendar.com