This can be solved with only these 2 items.
I recall learning in elementary that you can magnetize a metal rod (rod B) by running a magnet (rod A) over it several times in the same direction. While, if you run a single point of a metal bar (B) over a magnet (A), the entire metal bar (B) will not become magnetized. By attempting to magnetize with the other, you could tell which one was the magnet (A), by simply attempting to get the polls to push away after trying to use one to magnetize the other. If you find that neither of the ends of the rod that had been ran over the other repels one end of the other rod, then you will know that the rod that was ran over the other was not a magnet.
Thankyou Timm, as I read the question this is exactly what I thought of as well. Assuming what you say is true about magnetising an iron rod (which I also learned), this is logically sound.
Edited by robbo2050, 01 June 2008 - 07:58 AM.