Modern day method to waste time and 'recap' over all those topics you've been 'learning' all year usually in preparation for a text or exam. For most students, resulting in no help whatsoever when sitting the test the next day.
Thus student failing test anyway because revising is innefective due to student thinking about their crush/dinner/myspace/friends for the duruation of the revision period whilst blankly reading through text and making notes they will later misplace.
''But didn't you do any revision? why have you gotten this U again Eleanor?''
A 'relivent' subject 'taught' in high schools designed to ideally make sure you can't get into collage after failing it in your exams due to the teacher you had being an irresponsible, irritating, uncaring, potentially unqualified hater of children.
Chemistry was the reason she lived in the convent.