Why you need to know about ratios?
Nowadays, most PCs and Laptops are widescreen. But the majority of projectors on the market have an aspect ratio of 4:3. The term aspect ratio refers to the ratio of a picture's width to its height. If the aspect ratio of a picture were 1:1, the width and height would be the same, and you'd have a perfect square.
The aspect ratio of 4:3 means for every four units of width, the picture will be three units high as shown in the following screenshot.
What this means for your Prezi
Essentially what's happening here is that most of us are designing our Prezis on a screen that is much wider than the projector being used in the end result. What happens then is that our Prezis end up with lots of empty space in each frame or elements from other frames creeping into view because the frame isn't the right size.
The following screenshot is an example of a Prezi being designed on a widescreen laptop. It's a very common mistake to try and fill the screen with content and...