I second aeh. For certain subjects such as math, it is very hard to learn new things as deeply as you need after 25.
I'd like to see some research on that subject. I'd also like to see if anyone has investigated HG+ people and their ability to learn as they age. I know that that average age of Nobel laureates has
gone up over the past hundred years.
Personally, I find myself better able to learn some things in my late 40s than I was in my early 20s. Other stuff that was always very easy for me (e.g. languages) still is. But that's just me.
I think the root of the problem that the college professors are facing is K-12 education--students of cuddled too much in high school and they are not prepared.
I agree that K-12 education isn't doing a great job of preparing students for college (especially the bright ones). I don't think that coddling is the issue though. I see low standards and breathtakingly poor textbooks as shouldering a lot of the blame. You should see my daughter's algebra book. Besides having ADHD, it's a dog's dinner of mashed up ideas (e.g. the authors don't seem to know the difference between
concepts of algebra and
applications of algebra. This leads them present the applications before the students understand the concepts.). Most of the math books published in the last 15-20 years or so have this problem,* and I honestly don't know how anyone could learn algebra or geometry when relying on these books and a course that teaches straight out of the book (which my kids' teachers typically do).
*I collect math books.
