Well, let's try another way to join all dots. Oh, this also does not connect all 9 dots with 4 straight lines. Again one dot is left. Remember, we have to pass lines through all dots.

We've all done connect-the-dots puzzles. An array of dots is presented, each of which is numbered, and the task is to begin at number 1 and draw straight line segments until you get to the end ...

If you can see all nine dots at the same time, then chances are you have better-than-average peripheral vision. You'll most likely be able to clock things out of the corner of your eye that others ...

This puzzle is extremely difficult to solve if you see the nine dots as a box that you cannot go outside of with your lines. For those attempting this puzzle for the first time, that is the key ...