No apologies for choosing a bit of an obvious riff for this week's lesson. It's possibly the greatest riff of all time and one you need to know how to play if you're remotely interested in rock or metal guitar. There are many other lessons for this song on You Tube but from what I've seen a lot of them don't get it quite right, so I still felt it was worth doing my own version. Visit the lesson page to get started - it's loads of fun to play. I've also written out the rest of the riffs in the song.
Interesting bit of Sabbath trivia: the robot voice sound when Ozzy says "I am Iron Man" at the start of the song was achieved by him recording through the blades of an electric fan.