There's something out there on teh Intarwebz called "the Machete Order" as the way to introduce someone to Star Wars who knows nothing about Star Wars.

Watch Epi-IV, then Epi-V, skip Epi-VI for now and watch Epi-II and Epi-III instead, then go back and watch Epi-VI.  (Machete says skip Epi-I entirely).

That way you don't spoil Epi-V.  And after Epi-V you go back and watch how Anakin became Vader and wrap it up with his redemption in Epi-VI.

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