While American or Italian teachers would use the upper part of their grading scales (albeit in different ways), others (e.g., French and British) in practice hardly ever use the top 20% of their scale. For this reason, proposals based on linear formulas can produce devastating results: I recently saw the case of a German student in France who achieved a 15 (quite a good grade) which was converted into a German 2.5 (a rather mediocre one); on the contrary, a British student who gets a 27/30 in Italy would have every reason to be pleased if that grade were linearly calculated to correspond to a British 90/100! • Many grading systems are not continuous but divided into several "classes" or "categories" which correspond to broad levels of performance. This means that a small difference in numbers may conceal a substantial difference in meaning when a "class" limit is crossed: in the United Kingdom, a grade of 70 classified as "First Class" is very different from a 69 ("Second Class"), while the same small difference of 1 point is irrelevant between the grades of 54 and 55 (both "Lower Second Class").