Overwhelmingly positive! I had made the kids promise not to tell what was coming (and most kept the secret!), so the kids received a package in the mail from their piano teacher. I told them it was up to them whether to keep it a secret until Christmas, or to let their parents see what was in it.
I don't think any of them waited!
The parents came up to me over the next couple of weeks and gushed at how good their kids sounded. The kids (epecially the 5 eyar old twins) were just bustin' out with pride on how thye sounded.
The one exception was one of my adult students, who didn't know I had recorded her (she'd have gotten too nervous) - she wanted to sound better than that, and was very aware of her mistakes. This is common in adult students - we as adults are aware of where we are in the process (kids are just focused on the moment).
I suggested she treat it as a snapshot - and can play it in 6 months to compare how much better she is then.
Was it worth the effort? Oh, yes.
Lessons learned from my viewpoint? That's the next entry.
