Hi, I'm giving a powerpoint presentation for the first time next week. I've got my slides set up -- I plan to advance them manually and then run the animation (once I advance to the next slide, i'd like the animation to run itself, but in testing it it doesn't do that), but my question is: How do I make sure the screen is blank in the few seconds it'll take me to find and hit Play? Otherwise the screen shows the end result of the animation.