The answer should actually be preparation & transparency. If a school prepares its curriculum well in advance and tells every interested party "this is what we

The answer should actually be preparation & transparency. If a school prepares its curriculum well in advance and tells every interested party "this is what we expect and this is how we measure the success of learning" then there can hardly be any grade inflation. Either the school sets ridiculously low targets or it fails to be transparent. Note that missing success in learning can be caused both by the students and the teachers (or school). Grades are a way to measure that success and do not necessarily reflect on one or another.