The Associated Press Ana Homayoun, author of the book “That Crumpled Paper Was Due Last Week,” works with a student in San Francisco.

NEW YORK — There’s a reason why a new book about helping disorganized teenagers was published midway through the school year, rather than in September. ‘‘When you go back to school in September, everything is fresh and everything is new,’’ said Ana Homayoun, author of ‘‘That Crumpled Paper Was Due Last Week’’ (Perigee/Penguin, $15.95). ‘‘But now you’ve got first-semester grades,’’ and that can be a reality check. Midwinter is also a good time to establish new habits for what’s left of the school year, and getting a handle on all the crumpled papers lurking in backpacks, folders, desks and elsewhere is an important first step, Homayoun said in an interview. ‘‘We typically recycle a few brown paper bags full of paper in the course of going through their backpacks and organizing their binders for the first time,’’ said Homayoun, founder of Green Ivy Educational Consulting, based in the San Francisco Bay area.