I had a lot of fun working with my high school jazz band this last year on understanding guide tones—with the small group that I had, it was a ton of fun to dig into some concepts that I wish I would have worked harder to grasp when I was in high school. However, most of the group did not have a significant amount of experience with jazz improvisation, and they started the year very hesitant to improvise. Working with the group helped me realize how much teaching improvisation is like teaching anything else. You figure out what the student knows, look at what you want the student to be able to do, and then break down the steps in between to manageable chunks. So for today, what are the first steps in teaching improvisation to beginning students?
One of the ways I like to encourage improvisation early on is through varying what students are already playing. For instance, I am a big fan of rhythm exercises in beginning band. Many books (I have used Essential Elements in the past) include pages of rhythms in an appendix in the back, and I start using these pages almost right away. While I mix it up with speaking and clapping, when it comes time for students to play a line of rhythms, I start to work in some choices.
"Pick your favorite note and play measure 3." (at this point, they probably know only five notes)
"Great job. Let's trade off every other measure, and you can play any of the notes you have learned so far." If the student is doing well with this, I'll start changing notes in the middle of a measure to see if they'll experiment more.
At this point, I'll also work in some repeat after me, both with myself and the student(s) leading. Perhaps I'll play Hot Cross Buns as we have learned it, and then I'll throw in an extra note or a slightly different rhythm. At the beginning stages of improvisation (and particularly when the student is a beginner on their instrument), my goal is to make them feel comfortable following the instructions I'm giving.
The Essential Elements for Jazz Ensemble book uses a similar approach, and I have my beginning jazz players do the same kinds of exercises. We'll play Jingle Bells and then have students "solo" by varying the melody. Stronger players usually have no trouble with this, but I think it is important to reinforce the concept of variation in working with beginning improvisors. Until we are freed from technical limitations on our instrument, we can't play what we don't know how to play.
Over time, I'll work in additional listening exercises as well as chords, scales, and theory. That discussion, though, will have to wait for another time.