I like the glasses analogy. And glasses are so common nowadays, it's something a teacher sees every day (and possibly uses herself).
On the other hand, sometimes even things that should be obvious aren't. My DD has been dot at the bottom of the size chart all her life but the band teacher really wanted her to play trombone. I said, "But it's is bigger than she is. Her arms aren't long enough to play it properly." But this teacher had convinced my daughter she was born to play trombone, and had a trombone to lend, so whatever, it's free. After half a year, the band teacher finally says to my daughter last week, "Maybe your arms just aren't long enough." LOL, you think?
