It is often difficult to distinguish price discrimination form different prices for differentiated products. For example, if teachers recommend the magazines they read to students, they are helping to market the magazine. Because they save the magazine some marketing costs, it is profitable for the magazine to encourage teachers to subscribe by offering them a lower price. From the firm's viewpoint, a magazine sold to a teacher is a different product from a magazine sold to someone else. Can you explain a student discount from museums by appealing to this "different product" argument?