People were shown a bunch of writing purporting to make various claims about facts about the world, then were asked later which facts they believed.
It turns out when the writing was written in better prose or with better penmanship, people were more likely to assess the claims made in the writing as true.
This is evidently an example of a psychological finding that people are more likely to believe something as true if it is presented in a way that reduces cognitive load (e.g. by reading easy-to-read sentences or easy-to-read penmanship).
So, to get good grades, write clearly and legibly.
- Thinking Fast and Slow (2011) by Daniel Kahneman