Is saying ‘check’ allowed in tournament play or can it be considered a distraction under the provision that players are not supposed to talk to opponents?
Just wondering on how to instruct the young ones.
It is not mandatory to announce check, but it is not proscribed by the rules, either. So, it’s your call, I think.
FWIW, I would advise not teaching them to announce check. It’s one less thing to think about. In time pressure, it could potentially become annoying to the opponent and other players nearby, especially in major-piece endings. Finally, it’s not their responsibility to point out check to their opponents. Nothing wrong with expecting an opponent to notice check on his king. 
I say check. I say j’adoube. I say checkmate. I never say sorry.
In time pressure if you don’t announce check your opp may make an illegal move inadvertently and punch the clock. Then what?
Then you get your 2 minutes.
I consider it a bit inappropriate, because it is a gratuitous annoyance.
The USCF rules should discourage saying “check”.
Saying check was once a fashion, but that is not justification for perpetuating the habit.
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Saying, “Check.” is not necessarily an annoyance and certainly not necessarily gratuitous.
I have played many rated games where the saying of Check benefits the player whose King has been placed in Check. If the player does not notice the Check and makes a move which does not answer the Check, he then will make an illegal move. When his opponent says, “Check.” that alerts him that he is in check and must deal with that.
It was once polite in chess to say “gardez la dame” to warn your opp that his queen was hanging. Now it would be impolite if not illegal.
I normally don’t say check, but if I see my opponent apparently reaching for a piece that has no legal move, or whose only legal move would be disastrous (such as interposing the queen to a bishop check because that would be the only legal queen move), then I quickly say check to avoid problems – either rules problems or sportsmanship problems.
Bill Smythe
It was once a courtesy and a custom to say “Check” to one’s opponent. This applied not only to novice players, but also was a simple practice observed by the great masters. Saying “Check” was done quietly so as not to disturb other games. The official rules do not require noting that a King is under attack. Most tournament players do not say “check”, especially in time pressure, hoping for a miscue and an extra 2 minutes on the clock. Courtesy in tournament play IMHO is becoming more an exception than a standard. People like to cough on your move, kick the table, kick you, bang clocks and pieces, etc. … anything to get an edge so that they can win a trophy or a cash prize.
As noted above, it was also a courtesy to say “Check” to the Queen. That practice was generally discarded over a hundred years ago. I say it teasingly during casual games which usually confuses my opponent at first. Sooner or later I win his queen anyway, but at least he was warned!
Thanks for the answer(s). 
When you attack your opponent’s queen, maybe you should say “queck” instead of “check”.
I was once forced into a draw by perpetual queck. My opponent kept moving her rook back and forth between f3 and g3, perpetually attacking my queen, and my only reasonable response was to move my queen back and forth between g6 and f6.
Bill Smythe
In correspondence chess you could say the queck is in the mail.