Ever been to a themed party? Perhaps "Under the Sea" strikes your fancy. Imagine all the possibilities. You and your buddies could dress as sharks, clownfish, or manatees. Or maybe fictitious animals are more your thing? You could hit the party as a mermaid, the Loch Ness Monster, or Ursula (the sea witch).
Math can also have variations on a theme. Two variables (usually x and y) can have all kinds of different relationships in an equation. The most basic type is direct variation. Others include inverse variation, joint variation, and combined variation. Like we said, lots of variations.