This is a video guide that accompanies Modern Marvels Medical Imaging. I use something like this when I need a break or if I have a sub. There are approximately 30 questions that go in order with the video. An answer guide accompanies this worksheet. Modern Marvels videos can be found on the History Channel or the videos can be purchased online. I found this Medical Imaging on Amazon. These videos are perfect when you have a substitute because the videos last about 45 minutes.