The story goes that if you say ‘good morning’ to a class of elementary students, they will return the greeting; if you say it to high schoolers, they will respond ‘what’s good about it?’, and if you say to a class of college students, they will write it down. 🙂
I’ve had some experiences with enough students of all ages to recognize the kernels of truth hidden in that humor.  Naturally, it’s risky to draw general conclusions too rapidly, but it’s worth exploring this a little further.
Years ago I/we ran some “Fun with Math” classes for grade schoolers on Saturday mornings.  As you can imagine, these kids had vast storehouses of energy (antsiness?), and not surprisingly, it was hard for them to sit still!  (Once again I was reminded of our system’s criminal tendency to load down an elementary teacher with dozens of these kids in each class.)  Ah, but this energy and enthusiasm translated into a genuine curiosity that was fun to harness, an eagerness and willingness to try new things and very little of what we would call ‘fear of failure’ which would inhibit their learning.  As a result we had a great time and learned a lot of neat things. (And I always napped those afternoons!)
On the other extreme – at least age-wise – are the adults I often encountered who were back in school to finish a degree (or certification), often under trying circumstances.  Over the years, I really came to love working with these students.  Clearly the most ‘dedicated’ of the various ages, they were focused, knew what they wanted, and were often willing to overcome their fear of ‘math’ in order to get it.  They also exhibited curiosity, but in a subtle, different way.  They wanted to know how ‘this stuff’ applied to their world, and what they were ‘supposed’ to know for the test.  They were definitely dedicated, but more narrowly, and alas, the pure fun of learning had long since gone. They were the least likely of the age groups to view education as anything but a rigorous (and often costly) path to an end.  (Ironically, these were often future teachers.)
Interestingly – tragically – the least ‘alive’ age-groups were the young adolescents in late high school (I taught a year of high school Senior Math between my years at C of O and MSU) or early college.  Here were the experienced veterans of over a decade in ‘the system’, and they moved through the classes as if responding blindly to a distant unspoken set of rules.  Curiosity about the subject hardly ever surfaced, not because it wasn’t present, but because the students had learned that curiosity doesn’t pay, isn’t worth the energy, doesn’t get ‘the grade’.  With some effort, I could occasionally see – even induce – the sparks of fire that used to blaze back when they were youngsters learning to sit still, but it was an uphill battle.  There were often great kids – and bright, too! – but to them, getting educated meant riding out the system mechanically for their remaining years.
Yes, these are over-generalized snapshots, but I’ve seen the same distinctions and differences often enough to know there’s too much truth in this evolutionary overview of our system.  What happens to our kids as our system educates them (and what does it teach them)?  Do they have to lose their eagerness and curiosity when they learn to sit still? (Do they really have to learn to sit still?)  How can we nourish, rather than stifle, their love of learning?  As always, these are tough questions, and answers are buried deep.  But shouldn’t the search start with the next ‘good morning’?