Single displacement reaction in metals
The hypothesis that a more reactive metal will displace the salt compound attached to a less reactive metal, is proven to be true.
Metal ore contains lots of sand impurities and oxides. Displacement reactions are a useful way of extracting the metal from its ore.
This science project can also be repeated using other metals like aluminum, tin, etc.
Single displacement reaction - http://en.wikipedia.org/wiki/Single_displacement_reaction
Reactivity series - http://en.wikipedia.org/wiki/Reactivity_series
Basic safety requirements.