Alliteration- n. The repetition of the same sounds or of the same kinds of sounds at the beginning of words or in stressed syllables, as in “on scrolls of silver snowy sentences” (Hart Crane). Modern alliteration is predominantly consonantal.
Assonance- n. The repetition of identical or similar vowel sounds, especially in stressed syllables, with changes in the intervening consonants, as in the phrase tilting at windmills. www.answers.com
You can find lyrics of a song, nursery rhyme or in a book that shares several examples of alliteration or assonance, or you can make up several phrases of these forms and use them in a story that you create. You can find these concepts in the rhythmic lyrics of music, prose and poetry.
Give your child a bell or rattle. Share with her some examples of what alliteration and assonance would sound like. Tell your child that you are going to read her a story and she should listen for several words together that have the same letter sound. Every time your child hears alliterative or assonance words, your child should ring her bell or rattle.
You could even create several phrases using alliteration and assonance and give your child two different noise makers (bell, rattle, whistle). Have your child make a noise when she hears alliteration and a different noise when she hears the assonance phrase.