How to separate a mixture of sand,salt,water,oil, iron filings

First, you need to understand what is soluble in what. From the materials you provided, salt will be dissolver in water, producing a homogeneous solution - the hardest to be separated. Oil will float above water and can be easily separated using a funnel or by scoping. The sand and iron will be at the bottom, so at the end you will have a three phases solution.

After separating the oil(separated using a funnel or by scoping), you will filter the water plus sand and iron. After drying the sand and iron, you can separate them with a magnet. By last, in order to separate salt from water you'll have to boil it and condense the water.