Which tv channels can I suggest my students to watch in order to improve their English?

I agree with the national geographic suggestion

National Geographic channels are awesome for that purpose .

Depending on the level of education, you can either use BBC, NBC, CNN News channels ,VOA (Radio) for adult lerners or Spacetoon English, Boomerang and Nickelodeon cartoon channels for kids and younger leaners on satelite TV Networks. They are entertaining and funny at the same time; something which can also help the learners improve their accent and stay focused.

I think BBC and CNN. also Aljazeerah English.

Are there any channels for teaching English language to foreigners ?