There was some controversy a few years ago in which a number of schools abandoned competitive sport, preferring to emphasise "co-operation". In my view this shows a complete lack of understanding of the concept of Competition, which is a highly evolved form of co-operation.
If I play a game of chess against a player who, either by intention or incompetence, allows me to capture all of his or her pieces, there is no enjoyment for either side. Both sides need to agree to try their hardest, within the framework of the Rules, to beat the other, and in this way there can be great benefit to both sides. In this respect, opponents are co-operating in combat and I believe that this agreement to battle against one another exists all competitive sports. This "intellectual conversation" transcends the barrier of spoken language.
Although I prefer to win, I can think of examples of chess games that I have lost which have given me a great deal of pleasure simply because both sides played well and the outcome was in doubt for a long time. The games which I do not enjoy are those in which both sides have played badly and these are eminently forgettable. There is a small number of games which are burned indelibly on my memory in which both players have played well for a long period but I have then lost the game as a result of a simple, stupid, oversight. These are the hardest defeats to come to terms with, because there is nobody else to blame apart from myself.
There is a small number of games which I have played during the past 30 years or so which I have won through good play and in which my opponent also played well. These games are the most satisfying and I am not sufficiently modest to keep some of these games out of the public view!
We need to consider how young children will react to the slings and arrows of outrageous fortune.
Some children simply cannot accept defeat and I have known a number of young children (and adults, for that matter) who have opted out of chess rather than compete, even though they clearly have considerable aptitude for the game. If you identify players who fit this description, then do not force them to play. No one should ever be forced into a competitive situation against their will. There is plenty of chess material for them to enjoy in the form of studies, puzzles, etc., although this may well imply more work for you as a teacher in supplying them with interesting material. It is my intention to place a large quantity of such material on this website.
Some children lose almost every game and do not seem to learn much at all, but they keep on playing. There does not seem to be a direct correlation between chess ability and intelligence - it is just that this aimiable, hopefully cheerful group of wide-eyed innocents simply lack the low cunning which is an essential pre-requiisite of a chess player.
Some children do not seem to mind too much whether they win or lose, but gain a good deal from the social side of chess and improve steadily but not rapidly. This group probably represents the majority.
There are others whose hatred of losing is more than counterbalanced by the determination to win. These players become Grandmasters.