Harry Potter party for 8 year old. The birthday we near Halloween, so we could shop for various favors. We used Harry Potter themed invitations from a local party store.  The different rooms in the house were designated different parts of Hogwarts.  The loft was Diagon Alley; the dining room the great hall; the basement was the dungeon, and other rooms were classrooms.   As the guests arrived, they were sorted by using a felt wizard's hat with a "Hit Clips" recordable MP3 player hidden in the tip. As I placed the hat on each child's head, I could trigger the "Hit Clips" to announce a house. After sorting, they were sent to Diagon Alley. The door to the loft was surrounded by cardboard blocks with a brick pattern on them. Red and gold crepe paper streamers covered the entrance.  Upstairs they found Ollivander's, where they made wands from 9" dowels, using double side tape and glitter (it takes too long for glue to dry, and they needed their wands). They also made wizard hats from precut sheets of black poster board, rolled to fit each child's head, then decorated with stars, moons, etc.  An adult friend painted faces, while everyone finished up. When their clothing was complete, it was time for class. Charms class taught them 2 spells: "Revolvo" caused a (magnetic) stir bar to begin rotating in a beaker over a stir plate hidden in a table.  "Wingardium Levioso" caused a helium balloon to inflate and fly away.  To pull this one off, stuff the balloon into a cooler full of dry ice: it will rapidly "deflate" as the temperature of the helium drops, and lose bouyancy.  Pull it out JUST before the incantation, and it will appear to inflate and float. Transfiguration class turned "flobber worms" into "Gryffindor swords". Use balloon animal balloons as the worms, and show the children (and the adults, I bet!) how to twist them into swords (instructions available in many library books, or over the web; try ASK.COM)  We then went to the dungeon, decorated with plastic candles and flicker bulbs, for Potions class.  We taught them to make water disappear with the "Evaporate" spell.  To do this, take a damp sponge, and cut it into a circle that will fit in the bottom of a paper cup.  Place the sponge under the heaviest weight you can find, and allow it to dry. Crush it flatter with a rolling pin.  Put the sponge in the bottom of a paper cup, and cover it with a false bottom made from the bottom of another paper cup. Show the children the "empty cup"; here's where low light is a plus. While directing their attention to your assistant getting some water, invert the cup and tap it to remove the false bottom.  Invite the birthday child to the front; pour water into the cup, hold it over their head, and ask the guests to recite the spell.  Maybe get them to do it twice; it takes awhile for the sponge to absorb all the water. Then invert the cup. No water comes out!  From here we made a secret potion of snake's blood (vanilla); diamond dust (sugar); bovine essence (milk and cream); and shark's teeth (chocolate chips). Have the guests each add a portion of the ingredients to a LARGE, METAL bowl.  I then added dragon's breath (liquid nitrogen) to the bowl, and stirred rapidly.  The potion was instant chocolate chip ice cream!  Dig in everybody!   We then went to the great hall for our feast of cake, and pumpkin juice (Orange drink). We wrapped it up with a Quidditch game. Suspend hula hoops about 30 yards apart. Each guest used a broom (purchased at a local party store as a Halloween decoration). We put out a bag full of blown up balloons for the kids to throw through the hoops. Periodically, we would toss around a badminton birdie as the "snitch", to see who could pick it off.  The game ended when all the balloons had been popped. For favors, we used plastic cauldrons from the party store to hold bags of "Bertie Bott's" (Jelly Bellys), Chocolate frogs (hand poured; molds available at candy shops), Harry Potter diaries, Harry Potter style plastic glasses, and "Sorcerer's Stones" (large colored jewels).