Sack races are always great fun at parties.
Start by getting hold of some large, strong sacks. Draw a starting line and the finishing line. The game can be played individually or in teams. To make it fair for all kids, you can draw different starting lines for each age. The older ones can start from a starting line drawn several metres behind the younger ones. At your signal, the players dash towards the finishing line. The first one to cross the finishing line is the winner.