It was off-beat off Broadway first and it comes as a surprise to find these poem-plays and happenings being listed by the publishers at the 11 to 13 age level. But it's really not such a shocking surprise, after all. There is exceptional humor here, different and fresh, visual and vital. You also have to run to get with it, and kids do manage to run better than adults. When there was a Greenwich Village vogue for this sort of production, part of the pleasure in attending was to hear the comments of the more earnest, intense members of the audience. Some of them were desperate to locate an exact, profound revelation of cosmic truth. That attitude seems as deadly as its obverse, which would dismiss the whole undertaking without recognizing its ability to entertain, stir the mind to puzzlement and finally, to influence art. Here's an example of the sort of poem play that drives commentators to take extreme positions in praise or blame: A Beautiful Day. "Girl: What a beautiful day! The Sun falls down onto the stage. End." The woodcuts of Antonio Frasconi lend a strong, happy support and follow the sun theme of the poems. The audience doesn't wait, it's in the process of being formed and the book's greatest use among youngsters will probably come from talented teachers. It should also find its way to what seems to us the most logical appreciative readership--college students with a taste and curiosity for the avant garde.