A form on culture sounds interesting. Mind you, English is a tool for international communication, so it really isn't all that necessary for speakers to know anything about its associated cultures. That is, when Chinese and Japanese meet to discuss business, the culture of their respective nations is what holds true. Neither Chinese nor Japanese behave in a British, Australian, or North American way. Language is culture, yes, but that doesn't mean the two can't be separated, as in when your dealing with a Lingua Franca; culture isn't all that applicable because it's possible to use the tool without knowing all that much about the culture.
 I'm not from either the USA or the UK, but in Canada there is not grade below D, be it D or D-, besides F. That is E and G and so on are not used. There's no reason to do so. Anything below the 50 mark is F, a fail. Each institute, and each teacher/instructor decides the scale. For example,
and so on. . .