Outside of the box

Difficulty: 4 of 10

The Infamous Brick Puzzle seems to be a favorite among googlers. With that thought, I present another classic puzzle that involves drawing lines without lifting your pencil. The Nine Dots puzzle is one of the most well-known puzzles ever. It is the origin of the phrase "Think outside of the box".
Without lifting your pencil, draw four straight lines such that they go through all nine dots (which, by the way, represent infinitesimally small points). This puzzle is just too famous, so presumably everyone already knows the solution? If not, I will never spoil it for you--I insist that you solve it for yourself! (But of course, I can't stop you from googling "Nine Dots puzzle".)

So once you've found the solution to the classic, there's still more! I give you two more variations: The Twelve Dots puzzle and the Sixteen Dots puzzle.

Without lifting your pencil, draw five straight lines through all twelve dots. You must complete a loop, ending where you started. Cross each dot no more than once.
The Sixteen Dots puzzle is identical to the Twelve Dots puzzle, only you must draw six lines.

If anyone wants to post a solution in the comments, I suggest listing the coordinates of where you're starting and ending the lines (since it would be difficult to post pictures). Just let the lower left point be the origin or something.

Solutions