How has classical music influenced rock music?

I'm a freshman music major in college. And every so often, my teacher mentions something about how much influence classical music has had on rock music. My question is...HOW has classical music influenced rock music? I hear him mention it all the time, but he doesn't really do any proper explaining.

I've looked for a couple of online sites but wasn't very lucky in finding any.

Perhaps someone could help :]

This is brief, but if you listen to, say, Led Zeppelin or Jethro Tull you can see how classical music is subtle (or not) in some of their works. Lots of rock songs have orchestration, horns, strings, harpsichord, you name it. Classical music was basically the music that these rock musicians grew up with, so of course it affected their music.

Rock music has its roots in Blues. Blues music is what inspired rock to begin with. Classical music did not offer a grounding to rock. Though classical passages have been used by rock bands as part of their opera such as Tommy by the Who. Some classical guitarist or practicioners ended up in rock bands and used their musical knowledge to help form some of the more complex melodies or harmonies and there transitions. But the bottom line is that rock originated from the blues and blues has its roots in the african and carribbean culture.

Orchestration does play a factor, but when music theorists mention this, they really mean the chord progressions. Have you heard the Pachebel Rant on YouTube? During the rant, what the comedian says is true, all of these famous rock songs are using a chord progression hundreds of years old. You can't escape it!

Check Howard Goodall's program on "twentieth century greats -the Beatles" on Youtube it's in bits but well worth a watch
He's done a similar program about Cole Porter, a highly significant bridge between classical and contempory music but I not sure it's there.

Because ofthe chords. Classical composers helped form the chords, like C minor, G, A, etc... Then it progressed from one style to another. There was Mozart a classical composer then Beethoven who made way for Brahms and eventually led to jazz then jazz to rock.