First explain how the various pieces on a chessboard move. 

Divide into Sixes and place opposing teams on opposite sides of the hall with a chess set in the middle

Designate one side White and the other Black

When you call out the colour, the first person in the Six runs to the board, makes and move and then runs back to his Six.

Alternate White, Black, etc.

The game is based on speed - to make a move as quickly as possible.

The first team to take a piece (or 3 pieces) wins.

Not all Cubs will be familiar with the game so will need help making moves.  The team that strategises and talks so that each team member knows what move to make will have an advantage.