carl hendrick , head of learning and research at wellington college , berkshire , has attacked the ` tidal wave of guff ' in classrooms .
these ` missives in mediocrity ' often tell pupils to ` live your dream ' and ` you can do it ' and ` be all that you can be ' .
cheesy slogans such as ` reach for the stars ' on posters in schools could be detrimental to pupils , it has been claimed .