Confusable words: tell/teach

I often hear ‘tell’ and ‘teach’ used incorrectly.

“Please teach me your phone number” is wrong. It should be “Please tell me your phone number”.

Just giving information is ‘tell’ or ‘inform of’ – for example “I’ll inform you of my schedule as soon as I know,” which is the same as “I’ll tell you about my schedule as soon as I know,” or “I’ll let you know about…”

‘Teach’ is much deeper; it means to help somebody to understand. For example, “Please teach me Einstein’s Theory Of Relativity.”

So, “Tell me the computer language used for making a website,” has a short answer: “It’s HTML.”
But “Teach me the computer language used for making a website,” requires a long course of study.

Of course, there are times when the difference isn’t as clear. For example, a foreigner in Japan may say “Could you tell me how to write your name in kanji?” or “Could you teach me how to write your name in kanji?” It’s not so sure how much he already knows about kanji. However, the first question sounds like a short answer is enough, but the second question sounds like you need to demonstrate clearly by writing slowly.