Okay, so they can all have some fun playing unique rhythms and melodies with one basic scale, and I celebrate that success. But as soon as you try to get them playing over changes, FAIL.
Plus, there is never enough TIME to really work that hard on improvisation, with concerts and festivals constantly demanding your attention. So, I went on year after year accepting "failure to teach improvisation" as the norm. And my colleagues all agree that it is normal. One teacher recently gave a jazz clinic at a music educators conference and said, and I quote, "Teaching improvisation in the jazz band is too challenging and time consuming, so I just tell my students to learn to improvise in their private lessons".
However, prominent jazz educators like Roosevelt Griffin, who works at a low-income school at which none of his students can afford private lessons, agree with me that not only CAN we teach improvisation in our jazz band rehearsals, but that we MUST.
1. Use numbers Instead of note names to avoid transposition confusion
2. Engage the kids in harmonious, riff-based group improvisation
3. Patiently allow some noisy chaos while all students practice improvising simultaneously
4. Start with one scale, but then move along with a prepared curriculum that covers multiple scales and chord changes
5. Make improvising over a 3-chord blues progression the ultimate goal
6. Develop ear-to-hand coordination through using sequential, graded jazz patterns
7. Use short jazz patterns and whole-song guide tone patterns
8. Introduce chord theory in a way that kids can "get it"
9. Teach rhythm section "comping" skills to the whole class
All of these (and more) are incorporated in the classroom jazz improvisation method Improv Pathways. It is serious about teaching beginners how to "play the changes", and it works. It is "kid tested" for effectiveness and for the "fun" factor. It passes with flying colors. No more failure for me!