It is sadly true that "the greater literary world treats children's poets as nonentities" (Sloan 2001: 46). I am in the middle of writing an MA paper discussing this, and I'd like, very briefly, to present a couple of thoughts.
What is poetry? Former U.S Poet Laureate Joseph Brodsky once said that poetry "provides one with an epiphany, or a revelation" (Carroll 1998: 5). Given that the less experience one has accrued the more will be experienced as revelatory, it follows that the younger a person is the more will be experienced as poetry. For young children each and every experience is a revelation. In other words, for young children the whole world is poetry, and anyone who interacts with a young child is in a sense a children's poet. Children's poetry basically represents the most profound interaction possible between literature and life; it renders the two indistinguishable.
This is borne out in the work of linguist Frederick Erickson, who has done pioneering work on the musicality of everyday speech. An implication of this is that "as a child grows, nursery rhymes and songs [and poems] provide interactional 'scaffolding' practice for the acquisition of speech because the stress patterns in those rhythmically stylised writing genres map over the slightly less stylised but nonetheless regular patterns of timing in the conduct of ordinary talk" (Erickson 2003: 15). In other words, poetry can quite literally help young children to communicate. It essentially takes the best bits of chocolate and vegetables and combines them: "young children take an instinctive pleasure in rhythm pattern and rhyme" (DES 1989: 7.1), just likes chocolate, except that it is good for them as well!
Poetry matters both to and for children.
References (snore!)
Carroll, A. et al, (eds.) 101 Great American Poems, Dover (1998)
DES, English For Ages 5 to 16: Proposals of the Secretary of State for Education and Science and the Secretary of State for Wales (Cox Report), National Curriculum Council (1989)
Erickson, F. 'Some Notes on the Musicality of Speech', in D. Tannen and J. E. Alatis (eds), Georgetown University Round Table On Languages And Linguistics 2001, Georgetown University Press (2003)
Sloan, G. 'But Is It Poetry?', Children's Literature In Education, 32.1 (2001), pp. 45-56