I am running lots of schools events during the last few weeks of the school term in Canberra, and I am very fortunate to have a number of chess coaches and teachers helping me out on the day.
As an arbiter my main role is dealing with illegal moves, and adding two minutes to the opponents clock (NB Kids are very good at spotting when their opponents king is in check, not so good in seeing if their own king is attacked). One event got off to a particularly spectacular start where each of the top 4 games had an illegal move played within the first 2 minutes.
However there were some extra special rulings I had to make, above and beyond the usual. In one game a player had just a king versus the opponents king and queen. He simply moved his king next to queen and when the opponent said "that's check", said 'OK', and took the queen to get out of check. Luckily I was watching and explained how chess actually works.
Another game ended with a disagreement over the final score (1-0 v 0-1). Apparently one player lost to scholars mate, but told his opponent that as the game finished so quickly, they would now have to play a 'longer game' instead (which then had a different result).
And having explained that it was impossible to checkmate with a King and a Knight versus a King, one player called me over, showing me a position where they had a King, Queen, 2 rooks a few extra pieces and plenty of pawns, against a King and a Knight. She asked me whether the game was a draw, because her opponent only had a King and a Knight. Without giving too much away, I explained that this only applied if she had only the king.