In french its: 6eme classe, 7eme classe, 8eme classe, 9eme classe, 10eme classe, 11eme grade, 12eme classe. (or grade for all but that's more slang.) for the actual words its six,sept, huit, neuf,...
In Spanish ''your in 6th grade 7th grade 8th grade 9th grade 10th grade 11th grade and 12th grade'' is "en su sexto séptimo grado grado 9 ° grado octavo grado 10 grado 11 grado grado y 12"