Theory:

A magnet attracts only certain materials, and some it does not attract. The materials are categorised into two types. They are,
Magnetic materials:
The materials that are attracted towards a magnet are called magnetic materials.
Iron, nickel and cobalt are magnetic materials. Magnetite or Lodestone is the first known natural magnet that contains iron.
 
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Iron
 
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Nickel
 
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Cobalt
Non-magnetic materials:
The materials that are not attracted towards a magnet are called non-magnetic materials.
Example:
Plastics, leather, rubber, and paper are non-magnetic materials. Even metals like gold and silver are non-magnetic in nature.
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Leather shoe
 
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Papers
 
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Plastics
Iron filings:
In experiments using magnets, iron filings are used. These filings can be found in the soil as well. When a magnet is rubbed on the pile of sand or clayey soil, some particles stick to the magnet. The magnet is shaken well to remove these particles of sand or soil. But, still, a few particles stay on the magnet.
 
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Iron filings in the sand gets attracted to the magnet
 
These particles are nothing but small pieces of iron called iron filings from the soil. In this way, small pieces of iron particles can be easily collected and used for experiments.