A magnet placed against the wall of a metal shed falls to the ground, where it attracts a nail. What is the most likely explanation for this observation?

A magnet is attracted to iron and steel, so it would normally stick to a shed wall made of either metal. Since it falls but still attracts a nail, the magnet is working; the wall is most likely made of a material that magnets do not attract. Therefore, the shed is not made of iron or steel.

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