When you buy a new textbook, especially one from a heavyweight like Cornelsen, your first instinct is usually to crack the spine, flip to Chapter 1, and start highlighting. But there is one tiny, often overlooked detail that separates the casual learner from the power user .
Most of these codes have an expiration date. Cornelsen is generous—usually 3 to 5 years after purchase—but I’ve seen old "passive" books from flea markets where the code was dead on arrival. www.cornelsen.de/ codes
That detail is a web address printed on the inside cover: . When you buy a new textbook, especially one