Invitations: Cut out miniature ball gown skirts from a piece of silk fabric and use ribbon for a sash. Glue them to cardstock or construction paper folded in the shape of a card. Write all of the party information with gold paint pen.
Decorations: Create a festive mood with black, white, and gold balloons and streamers. Attach silver stars to the ends of helium-filled balloons so that they hang down from the ceiling. Tape up pictures of musical notes and silhouettes of ballroom dancers. Set a fancy lunch table with music-note-themed paper goods (from your local party center) and plastic champagne flutes. A paper top hat tied to a bouquet of balloons makes an elegant centerpiece.
Activities: Have the guests dress up for the occasion. Or make basic ball gown skirts with sashes using remnants and trims from a local fabric store. Have white gloves and extra jewelry for the guests to wear when they arrive. Hire a local dance instructor to teach the young ladies (and gentleman) some basic moves such as the box step or a simple swing. Then turn them loose to cut a rug on the dance floor.
Snacks: Serve elegant but kid-friendly finger foods such as mini quiches, pigs in blankets, and chicken skewers. Fill the champagne flutes with sparkling cider. Have candy-coated chocolate mints on the table.
Birthday Cake: Dazzle the birthday girl with a homemade chocolate cake topped with a circle of chocolate-dipped strawberries for dessert.