OH! I am in 7th grades the other time i said 5th grades i inversed bc i am french, we do not have the same things... Like 4th grades mean CM1 5th grades mean CM2 6th grades mean sixth (French= sixième) 7th grades mean seventh so in french cinquieme! (you can google it) Like in your country we go to 0 at 11 or 12 but us it's "CP, CE1, CE2, CM1, CM2, Sixth, Fifth, Fourth, Third, Second, First after there is the "bacalauréat (bac for short)" in english it's baccalaureate...
If you want more information search in google bc it's better at explaining then me xd!