Ducking Contract :
After South's opening and noticing that there is a misfit in major but 26 H points in the two hands, there should be no problem in bidding 3NT; up to the other side to lead the fourth highest Diamond (advice 15.1) (advcie 15.2).
Those who fail the contract are those who have decided that they must establish Clubs at any cost; you must explain that they were not wrong but to show them that they were in danger right from the lead in a suit in which the side is very weak.
Find with your pupils the probability of a long Diamond suit in the leader's hand and get them to deduce the number of Diamonds in the hand of the player to the right…
Explain to them now that the declarer, being able to make only a single Diamond trick, would be best served by making it as late as possible (advice 15.2); and after the demonstration, draw the conclusion that, in No-Trumps, the weaker you are in a suit attacked by the opposition the longer you should wait to take a trick.