Type “music intervals” into Google and you get over 5 million results, most of them useless.  They are either too long or too complicated or of poor quality or just plain wrong.  The best introduction to intervals I found was at pianolessons.com.  The YouTube video is below, or you can see the video along with a transcript here.

Basic Intervals

Missing from the presentation are examples of the intervals as used in well known songs.  If you are serious about your musical studies, these are important – they may be the only way (besides cheating) to pass an ear-training course.  Think of these songs as Nate plays the intervals, then go to the keyboard and play them yourself.  I have included the notes for each interval, using middle C as the starting note.

Interval Song References
minor second: C to Db Jaws theme, “I’m Dreaming Of A” White Christmas
major second: C to D Frere Jacque, Happy Birthday
minor third: C to Eb Rock A Bye Baby, To Dream The Impossible Dream
major third: C to E Oh When the Saints, Morning Has Broken, verse and guitar riff of “Blister in the Sun”
perfect fourth: C to F Auld Lang Syne, Here Comes the Bride, Hi Ho
Tritone: C to F# The Simpsons theme, Maria (West Side Story)
perfect fifth: C to G Twinkle Twinkle Little Star, Star Wars (Main Theme), Sprach Zarathustra (2001 Space Odyssey)
minor sixth: C to Ab The Entertainer (notes 3 and 4)
major sixth: C to A My Bonny Lies Over The Ocean, NBC theme
minor seventh: C to Bb Star Trek Theme, Mirage
major seventh: C to B Bali-Hai (1st and 3rd note) or Scary “Woo-hoo!”
perfect octave: C to C Over the Rainbow

[The minor sixth and major seventh are tough — let me know if you have better or more up-to-date examples. Not sure how may kids out there are down with Bali Hai.]

Start with the major and perfect intervals (the white keys above C).  Once you are comfortable with them, move on to the next two lessons:

Intervals & Octaves Part 1

Intervals & Octaves Part 2

So now we know that intervals are just the spaces between notes.  If you absolutely must know the mathematical relationship between the notes, and have always wondered what A 440 really means, the answers are revealed here.