Nonlinear Price Discrimination: There are two concepts included in this short section.  The first is offering discounts for buying in bulk.  In many cases this happens using a menu approach in which the firm makes different size packages available at prices that are lower on a per unit basis as package size increases.  The other concept is block pricing in which sets of units are sold at different prices.  It is worth showing students that block pricing with smaller and smaller blocks converges to the case of perfect price discrimination discussed earlier.