Create a maze out of staves (outside) or straws/earbuds/skewers (indoors).

Cubs (in teams of 2) to write instructions to get from the centre of the maze to the exit (eg. walk forward two steps, turn right 90 degrees, etc.). 

When they believe the instructions are ready, one member of the team goes to the starting point of the maze (or places an object in the centre of the maze if indoors)

The second member of the team calls out the instructions in order.  The Cub in the maze must follow the instructions EXACTLY.  Challenge them if the instructions aren't specific enough. 

If their programme is not correct, they can go back and rework it and try again.