The Little Girl
In this story, the little girl represents the reader, who is still learning to read but is progressing from very simple words and sentences. Seuss uses very simple rhymes and some more complex sentences, which transitions early readers into more difficult stories.
The Father metaphor
The father represents more advanced readers and the future of understanding language for the young reader. The father "can read big words, too. Like Constantinople and Timbuktu." These words represent more complex words, that the reader will probably need help with. There is a suggestion that these are the kinds of words the young reader will one day be able to read easily.
The Little brother metaphor
The little brother in this story is a metaphor for very early readers who are just getting to grips with language. The little girl tells us that her brother "reads a little bit. Little words like if and it," telling us that he has just started to read.