Colin Wood writes: “No one wants to pay $200 for a textbook, and soon no one will have to, because the $200 textbook may be disappearing. Like other technological trends that were plodding along before COVID-19, the use of digital resources and freely licensed learning materials—known as open educational resources, or OER—exploded in 2020. And that growth comes with an added bonus for students: For the first time in decades, textbook prices are dropping.”