After agreeing to nat's request to share her lecture notes from one class, maria now agrees to nat's request to share her notes from three classes. this example illustrates the .

This example illustrates the foot-in-the-door technique.
This refers to the fact that if you manage to convince somebody to do a small favor for you, they will be more likely to help you with something more engaging and important as well. As you can see here, Maria helped Nat with one lesson, but then she was more willing to help him with three.