Read your book report aloud. If possible, record yourself reading your book report and listen to it several times.
Pay attention to the rhythm of the words you've written. Make a note of a phrase or sentence that stands out rhythmically or a rhythmic pattern that repeats itself.
Tap out the rhythm of the phrase or sentence without speaking the words. Use your fingertips on a table, a pencil on a desk, or even your feet against the floor.
Notice any similarities between the rhythm you've tapped out and a simple song. For example, if you wrote a book report on "The Secret Garden" that includes the sentences, "Young Mary Lennox has just been orphaned. Her Yorkshire uncle takes her in," you might notice that its rhythm fits the song, "You Are My Sunshine."
Reverse this method and sing some simple songs. For example, sing "Twinkle, Twinkle, Little Star" or "Old MacDonald Had a Farm."
Rewrite the sentences in your book report to fit the rhythm of a song. For example, if you revise your sentences about "The Secret Garden" to fit the rhythm of "Twinkle, Twinkle, Little Star," you might write, "Mary Lennox was a girl who was orphaned very young. When her uncle took her in, she discovered something strange."