Originally Posted by ultramarina
Because he was done so fast, the tournament officials also asked him to play a K-5 player (4th grade) who did not have a partner that round; that game ended in stalemate. I don't quite get the mechanics of that part but it seemed to be okay by him.
You are stalemated if you are not in check but have no legal moves. Did your son administer stalemate or was he stalemated himself? You could ask him who had only a king (and perhaps a few pawns) left at the end of the game. Either way the result is a draw, but in junior tournaments the player who was stalemated was typically the weaker player, who got a bit lucky. When my younger two started playing in tournaments, some of their first non-losses were stalemates carelessly administered by their opponents.

Congratulations to your son on his result.