Re: a piece of chalk versus a chalk.
From that I infer that if you talk about chalk used in schools for writing on a blackboard, then chalk is uncountable. When you talk about the chalk that artists use (perhaps a slightly different kind of chalk than is used in schools?), then chalk is countable. Is my deduction correct?
Originally Posted by 5jj
I'm not a teacher, or a native English speaker. Feel free to edit my posts if you encounter any mistakes in them (be it grammatical or vocabular). It'll help me to improve my command of English.