What direction does air resistance act on an object that is falling straight down

Up

Explanation:

The direction where air resistance act will always be opposite to where the object is going.

Since the object is going down, the air resistance would go up.

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 : )