I recently served on a jury for a three-day trial. We spent four hours of that time watching videos of depositions from three different doctors. The plaintiff was asking compensation for back pain allegedly caused by an accident, so we heard lots of testimony about the state of his spine and back muscles.
Now, this was tough sledding for us civilians because none of the three medical experts used any illustration, 3D model, or photographs. When a doctor referred glibly to the T4 or the C7 vertebra, it was up to us on the jury to puzzle out what part of the spine he was talking about. Had he just pointed to the area on a diagram, it would have been easy to understand.
They are called “visual aids” for a reason; they aid your audience’s understanding. Imagine that your audience is hearing your line of reasoning for the very first time – because they are. Visual aids give your audience guideposts as they follow along.
Explaining a complicated subject without visual aids requires your audience to work very hard. Explaining a complicated subject by using visual aids = aha!