This is a video guide that accompanies Modern Marvels Water. I use something like this when I need a break or if I have a sub. There are approximately 25 questions that go in order with the video. This viewing guide is free because it accompanies only a part of the video. I believe it goes with the first 25 minutes (approximately) of the episode. Modern Marvels videos can be found on the History Channel or the videos can be purchased online. I found it at this link: http://shop.history.com/detail.php?p=69839&SESSID=cb1c85da432a5b00e63888cfc921c695&v=history. It sells for $19.99.