Interesting podcast (with transcript) at Grammar Girl about the "generic" (aka epicene or gender-neutral) pronoun: "they" with a singular antecedent. Grammar Girl is as perplexed as everyone else, but makes the very reasonable suggestion to simply rewrite the problematic phrase. Casting it in the plural usually works: Instead of "When a student succeeds, [he] [she] [he or she] should thank [his] [her] [his or her] teacher," you can write "When students succeed, they should thank their teacher" (or perhaps "teachers").
I've written about this problem myself and continue to find interesting articles about it. My gripe with singular "they" is that I see and hear it used all too frequently to refer back to a gender-specific subject, e.g.: "If a boy breaks the rule, should they be punished?" This is just plain sloppy, and evidence of an inability to think from one end of a sentence to another.