As a change from running a Treasure Hunt - here is a great childrens game. Follow the links for other party games to entertain your kids:

Hither and Thither

Draw two parallel lines as far as possible from each other down the length of the hall.

The players are divided into two teams and they each take up positions along the lines facing one another. The hostess blows her whistle and everyone runs to the opposite line as quickly as possible. The hostess quickly blows the whistle again, and they must change direction and run back, but before they reach the line the whistle blows again, and again so that the players are running forward and back, getting quite muddled as to which way they are going. Eventually allow them just long enough for one player to run back over his own line, that is the winner.