I think we should achivevment rather effort determine students` grades.
Because when student graduate facing the outside world,many thing decided by results,maybe sometime this way is unfair but it`s fact and they can not change temporary,so if
we chose achievement,studeny can get use to it more earlier,like some mental exercises,can be more stornger when they graduate.
Meanwhilehard work make achievement,and if it not ,it will finally.so by hard working or achivevment actualy is the same at last,just let the student be more stronger mental by achivevment way.