I know exactly what you're saying with the young ones. I'm a teacher and see it often, and not only with artistic ability... It's the same with intelligence. The think it is a matter of, you either have it or you don't, and so when they're having difficulty in a subject, they end up never getting better because they think they simply weren't born capable of understanding it.
This is why I always tell parents not to praise their children by saying "Wow, you're such a clever boy!" ... and instead emphasise the work that went into it... "Wow! .. You worked so hard on that! Well done!" in order to foster the truth that you can get good at almost anything if you just dedicate yourself a bit.
What a great minset to teach in. I'm glad there are people like you teaching young minds !