Build and fly model aircraft useing "Round the Pole" RTP flying methods. This is like scalelectric only with card or bolsa planes. It is necessary to obtain and build the basic RTP equipment well before the meeting and to properly test the equipment. Cheep planes can be made from old corrugated card boxes with the only the engines needing to be purchased and there are good guides on the internet.
You may whish to split this over a number of meetings.
RTP pole or poles (see Ballards RTP on the web) for two planes per pole
Lots of card & glue etc
Note that the kit is expensive and takes time to build. However, the cost items can be used over and over again!
Build and demonstrate the models flying
Split the Scouts in to small groups and allow them to build their own planes
Fly the pains (two per pole) and "dog fight" to find the winner
Mend the plans and start again.