I made this for my dad's twenty-second wedding anniversary, he likes puzzles and was quite happy with it. It's not hard to solve, the reason it is impossible is that there is two ways to solve it. One of the solutions leaving a mysterious hole.
Got it off Brusspup's youtube video check it out:http://www.youtube.com/watch?v=MxhD_9_FoPU
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.