You can talk about the origins of badminton (shuttlecock and battledor) and how the rules have changed over the years. You can find out (just google badminton champion) who holds the world title, and you can talk about badminton in the Olympics, and which country won at the last Olympics. It should be a whopper of a draw at the next summer Olympics in China, because they are fiends for the sport over there.

You can also mention the fitness benefits as a side effect.

Five hundred words isn’t very much at all — it’s about two pages and you’ve probably already got almost enough information to begin.

good luck