Comma Queen is video series published by The New Yorker.
In 25 episodes Comma Queen (Mary Norris) explains a number of controversial and difficult grammar points. The series includes videos on “I vs me”, “which vs that”, "dangling participle", "singular their", "prepositions", "less vs fewer", "who vs whom", and so on. It also explains the correct use of punctuation.
The videos are concise, clear, and come complete with examples.
Mary Norris also delivered the talk The nit-picking glory of The New Yorker's Comma Queen at TED early this year.
You can read the full transcript here.
H/T to Lesson Plans Digger.