My son usually can curve his fingers when playing just white keys. He started PA 1 unit 6 two weeks ago and he usually won't curve fingers when playing black keys because the small hands are hard to reach those black keys. T&A book says to walk up to the black key by raising wrist slightly. But it is hard to do that when the keys to be played is white, black, white, black with a fast tempo (like "the crazy clown" and "the crawling spider" in the performance book). Do you actually play it like "walk up", "walk down", "walk up", etc. to make sure use curve fingers to play black keys or it is OK to play black keys with extended fingers. Thanks!