Is requesting that goods be placed on shelves in exchange for taking the boxes considered a combination of an Ijarah (lease/hire) and a Hiba (gift)?

The act of the student emptying the boxes and placing the goods on the shelves in exchange for taking the empty boxes is considered a valid rental (ijarah) and not a gift. This is because the benefit is the emptying of the boxes, and the wage is the empty boxes themselves. It is not a condition that the wage be in cash; it is permissible for it to be in kind.