I might be doing a photography course next year and a requirement for the course is to have a telephoto lens.
It specifically says: "Telephoto lens (e.g. 55-200, 70-300mm)"

I just wanted to know are there other sizes for a telephoto lens? and if so could someone please list them for me?

I am thinking about getting a Canon EOS 600D and one of the twin lens packs has a 55-250mm lens. Is this lens considered a telephoto lens?