Studying the extremes of the spectrum of informational programmes can teach us about the nature (and limitations) of television. Analyse and compare any Open University programme and something such as the National Geographic film. Ask of each programme: is the maker's intention primarily to inform or to entertain?
Does the programme rely on a narrative structure, with a hero, mystery and suspense?
What use is made of charts and diagrams?
What part is played by sound effects, visual content, mood-and-atmosphere shots, and any accompanying music?
Is the viewer's attention engaged and sustained by appeals to logic or emotion?
What is "info-tainment"?
A text may help: search for "transcripts" at www.bbc.co.uk and www.cheops.org