Connect the Dots

How could you draw four straight lines that pass through all nine dots without lifting your finger from the page and without touching any dot more than once? A line must pass through each point. Can you do it? Most people have difficulty with this problem because they have a mental set to interpret the arrangement of dots as a square. They then assume that they can’t extend a line beyond the apparent boundaries of the square. Now that you know this, try again; does knowing that your lines can extend beyond the square formed by the nine dots help you solve the problem?