As Hermione rightly points out, the pronunciation of the incantation Wingardium Leviosa matters a lot in its delivery. Unlike Ron's pronunciation of the term, Hermione stresses the need for the "gar" sound in Wingardium to be nice and long and must be said as follows - Wing-gar-dium Levi-O-sa. The correct pronunciation of the incantation enables Hermione to levitate the practice feather way up in the classroom.