I'm guessing Mr. O. was a last-minute sub for our grade school vocal music class. It isn't usually a good sign when a teacher says, "Hmmm...What can I teach you?" Mr. O., however, looked at the piano and said, "I know what I can teach you," and gave the class an impromptu lesson on chords. At the end of class, he said, "So, when Mrs. S. comes back and asks what you learned, you'll be able to say, 'Mrs. S., I learned that a C major chord has three notes, C, E, and G. Also, Mrs. S., I know that a D major chord has three notes, D, F-sharp, and A..."
Granted, no student actually talks that way, outside of an educational short film from the '50s. Still, I remember that improvised music lesson more than 35 years later, so I guess it was effective.
