After you and your child finish reading a story together, close the book, and ask, "What do you think happens next?" or "What happens the next day?"
This kind of thinking helps your child in a few ways. It encourages your child to use what he or she already knows about a character or a situation and run with it—to spin some educated guesses based on that information. That is also called making inferences, which a skill your child will use in school and in life.
For now, unburdened by finding right answers, your child is simply stretching his or her imagination, and engaging in some original storytelling. Enjoy it together!