Ten coulombs of positive charge flow from the +9 V positive terminal of a battery to the negative terminal at +3 V. What is the charge in potential energy of the charge? A) 90 J
B) 30 J
C) 60 J
D) -60 J
E) No solution

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )