For me, it would be helpful to start the example by stating a goal, rather than starting right in with the XML. (I'm not sure I've got this right from looking at the image, but maybe something like this? )
For example, to set up an A/B Test that presents either a video or a multiple-choice question to students, you need to set up a total of three components. The first one is a parent, or container, component for the other two components, which present the video and the problem.