Four or five sentences are all you need for an 18-month-old. The world of babies and toddlers is very small: Mom, Dad, Grandma Susie, Jack the Dog, your home, Sesame Street, the grocery store, the local park, etc. Make up stories about these people and places — the swings at the park, Elmo from Sesame Street, your neighbor’s cat, or the sunflowers in your garden. Save flying carpets, sailing ships, and tropical islands for a few years later. The younger the child, the shorter the story.