Earvin (Magic) Johnson has signed a deal with Big Entertainment to develop children’s books and kidvid fare.Big’s goal is to develop textbooks and other educational materials featuring characters that can be spun off into TV shows and movies. Johnson, the NBA great who’s set to launch his own latenight talkshow next year, will have final approval on all products. Big has a number of similar publishing/development deals in place with such notables as Tom Clancy, Arthur C. Clarke, Leonard Nimoy and Mickey Spillane. Titles packaged by Big’s Tekno Books division have been published by Doubleday, Random House, Simon & Schuster and Warner Books, among other imprints. On the TV side, Big is developing “Tom Clancy’s Net Force” as a miniseries for ABC. “The anchor of the (Johnson) deal is educational textbooks that will be branded with Magic Johnson’s name, but we anticipate some of these projects will lend themselves to TV and movie properties,” said Mitchell Rubenstein, chairman of Big.