Math Problem

A farmer has a fox, a chicken, and a bag corn. He must ferry all three across a river in a boat tha will hold only himself and one other item. The chicken cannot be left alone with either the fox or the corn. How will the farmer take all three across the river ?

What must the farmer take across ?
(The chicken; because it cannot be left with either of the other two)

What must the farmer take across second ?
(either the fox or the corn)