To play the spanning puzzle, select Spanning Puzzle in the Options menu.
The object of this puzzle is to place pieces onto the board so that no additional pieces can be placed on the board. Such an arrangement of pieces is a spanning. The fewer the pieces you place on the board to achieve this, the better the spanning.
The spanning puzzle can be played on any board and with any piece set. As with the jigsaw puzzle, after you have placed a piece on the board, you can move it to another position on the board.
The computer will tell you when you have achieved a spanning. It will also alert you if you've created a personal best spanning. It displays your best spanning in parentheses in the status area. It also displays this number in the statistics window.
If you're still unsure of the concept, let the computer find a spanning for you. Select Find Spanning in the Commands menu. It will always find the same spanning, and it will usually be 7 or 8 pieces. You should be able to do better. For most of the boards, you should be able to span the board with 6 pentominoes.
Here's a sample spanning. Notice that the C-shaped pentomino could fit on the bottom of the board, but since it's already being used on the board, that's not possible -- so this is still a spanning (although not an optimal one).
Polyominoes Home Page