How about giving the winning grade that has the most students attend the game win an ice cream social or a no homework pass or something on that idea. Iknow at my school classses love to beat out one another. Good Luck sounds like a great event!
Ask one of your village officials to announce the players. The mayor, village president, etc., participating might peak the interest of local papers. Make sure you send info on the game to your community papers and community cable channel. If you're part of a homeowners association or you have community newsletters, send them info to. Find a way to get a sports writer involved. Do you have your game refs in place? Maybe they could be popular players from the local college team. Create a poster and ask the restaurant supplying the dinners if they'll post it the week before the game. Send the info to TV and radio stations that have community calendars (do they still do this? Now that I'm suggesting it, I haven't seen/heard these type of announcements in quite a while. I guess I'm showing my age, LOL).
Last week we had our first every faculty vs. 5th graders volleyball game. All the kids in grades K-3 we asked to make signs that they could hold up and wave at the game. They could choose if they wanted to root for their teacher or the 5th graders. Too cute! Kind of goes along with Kriswm's poster contest idea. I also like the idea of one or two big prizes to be raffled off at the end of the game.
Work on getting someone considered a celebrity in your area to be the auctioneer. Is there a really funny, popular, etc., anchor or reporter on your local newscasts? Many times they'll announce their involvement on air before the event, and bring a cameraman with them at the event.
make sure the game / rivalry is played up in the morning announcements. Come out and cheer on your champs.........who will win ?the the students with their youth and enerygy.....or the staff ...with skill and and experience/ stategy.....
maybe have the losing team wear t-shirts ....proclaiming the winners ROCK....
just a few ideas.
You could also get the students fired up by having a poster contest. Students create a poster (tell them what size paper or provide it for them) promoting the event and then pick 1 winner from both grades with 6-8 honerable mentions. Display all winners and honerable mentions in a prominent location of the school (front lobby?) and make copies of the 2 winning designs to post at various locations in your community. (Grocery stores, laundromats, etc.) You could also use the winners in an email or flyer sent to all student families a week before the event.
Another idea is to hand out numbered tickets at the dinner, buy 3 dinners get 3 tickets, and then have a drawing after the game is over for a prize. (Gift Certificate for 4 to the restaraunt providing the dinner, a bike, a digital camera, or tickets to a pro sporting event) That will help keep people there for the game if you say they must be present to win.