Visuals are incredibly powerful tools for teaching. But, you need to think about visuals alongside the text. Don’t make one element subsidiary to the other. Figure out what you need to get across and then develop a strategy for that idea. If you have ever written a label, you might have struggled on how to get across an incredibly difficult concept in words. For me, that challenge was explaining piece casting in words.
There is no fast and hard rule to do this well. I would guess you are using visuals much less than you could. I would guess engagement with ideas would go up if you used them better. But, don’t rely on my guess. Try some tactics. Tell your visitors that these are tests. Ask for feedback. Learn from your visitors and show your visitors that you are being responsive to their needs.
Here are some specific ways to use images. I could write them out solely in words, but that would do you a disservice.