Riddle: There are two bars of iron. One bar is magnetized along its length, while the other is not. Using just the two bars, without any other items, how can you tell which bar is magnetized and which bar is not?
Answer: Take the two bars, and put them together like a T. (Put one bar horizontally across and center the vertical bar under it.) Bar #1 is the top of the "T" and bar #2 is the vertical bar.
If they stick together, then bar #2 is the magnet. If they don't, bar #1 is the magnet.
Bar magnets are "dead" in their centers and there is no magnetic force, since the two poles cancel out. So, if bar #1 is the magnet, then bar #2 won't stick to its center.
However, bar magnets are quite "alive" at their edges and the magnetic force is concentrated. If bar #2 is the magnet, bar #1 will stick to it.