Here is a look at the role these keys play in the learning process: The Lifeline for Parents

"Gotovye domashnie zadaniia" (GDZ)—or pre-solved homework—for N.N. Derevianko’s English series (like New Millennium English ) is a staple of Russian student life. It’s a tool that sits right on the edge of "helpful resource" and "academic shortcut."

GDZ for Derevianko is best used as a . It’s great for checking where you’ve been and making sure you didn't miss a turn, but if you use it to steer the car, you’ll never actually learn how to drive.

Sometimes the "key" misses the specific nuance the textbook was trying to teach.