When I was 10, I came across the following problem in a puzzle book:

Can this "barn" be drawn without picking up your pencil and without drawing the same line twice?

After trying several times, I finally found that I could. From what we learned in class, can you answer the following questions:

• What property of this picture ensured that I would eventually find a solution?
• Can I start my drawing at any point? If so, why? If not, at which point (or points) must I begin drawing?
• Will I end my drawing at any point? Is so, why? If not, at which point (or points) must or might I end my drawing?