Where did all the high slides go? Ten years ago, Colorado photographer Brenda Biondo was at a local playground with her baby daughter and realized the equipment looked a lot different from what she remembered. As she visited other parks, she rarely found the traditional metal slides, monkey bars and seesaws of her youth. When she did, she took pictures. That search turned into a larger project, in which Ms. Biondo traveled to different states photographing old playground equipment. The results are in her new book, Once Upon a Playground.