On second and third readings, discuss the illustrations in greater detail, to help your child make the associations between the picture and the text. Stop occasionally to focus on a particular word like garden or bus. An older child can name the first letter in a word, then practice making that letter's sound. Explain whether the letter is a capital or lower case. A younger child can point to specific letters and name them.
Children often enjoy searching for the letters that make up their own names.
You may also want to ask your child to name other rhyming words. Write those words in a list. Then talk about how changing the beginning letter of a word can create a new word that rhymes. At the beginning, your child may paraphrase the book or skip over certain words. That's not unusual.