Anyway, here's my idea: explain the difference as a game. In one game, the Republic one, every player and judge follows the rules that are already in play. No changing the rules as they go along, everybody knows how to play, and the fans can cheer on. In the other game, Democracy, the players, coaches, judges and fans all vote on and change the rules whenever the majority of them want to. Nobody really knows what skills are needed for the game, since the game changes so much, the game goes more slowly, and then when someone scores a point that the majority (one team, the coaches, the judges, and the watching fans) don't like, they vote and take those points away. Also, the fans can vote on who wins, regardless of skill or sportsmanship.
I read recently that for a democracy to work, every member in the community has to be fully involved. This is not workable, since ordinary life prevents most people from deeply studying every single issue or bill that comes up, complete with complications and consequences involved with each bill. In a republic, a handful of representatives are voted on, and it's these representatives who carry the full-time load of handling the issues and bills and laws, while the ordinary people can continue won with their ordinary lives.
I know I can't be a working part of a democracy. I just look at all of the bills that come up before the House or the Senate, and my mind shuts down: I'd probably judge each one on impulse, not wisely. I'd rather handle the responsibility of choosing someone wiser than myself to represent me, then just simply see after the fact the results of that representatives' choices.
"Moderation in temper is always a virtue; but moderation in principle is always a vice." -- Thomas Paine