We all know that the Bb Blues scale is a tempting teaching tool. Kids dig the jazzy sound of it, but it has pretty limited utility in most jazz band solo contexts...unless they happen to be bluesy tunes in Bb.
Dig this montage of a young'un bluesing out on some well-known diatonic tunes.
Sure, it's easy to see how absurd this is. But, if you've ever attended a middle or high school jazz band concert, you would agree that it isn't far from what really happens on these stages.
So, back to the salt thing: A little bit of salt added to your food can give it just the zing it needs to taste amazing. But, if you add much more than that, you know what happens to the flavor. 'nuff said?
OK, rant over. Some positive alternatives would be to teach students specific scales or melodic devices that work with specific tunes. For instance, if a solo is F Major, an F Major Pentatonic scale is nice melodic structure that lends itself to great-sounding melodies. As would a C Major Pentatonic scale, for that matter. But, a Bb Blues scale on an F Major tune? Square peg in round hole.
So, it is indeed the teacher's job to recognize this situation and equip the student(s) with good information.
The truth is I've got LOTS to say on this, but I'll stop here for now. Your thoughts?