Reason/Evidence 3: Write one more sentence that supports your claim that students should speak up when they see someone cheat's on a test with a reason or a piece of evidence.

Honesty

Explanation:

Being honest is a good thing in itself. And there are pragmatic considerations in favor of honesty too: Dishonesty is hard to conceal in the long run, and in nearly every sphere of life, having a reputation for dishonesty is a curse. In most circumstances, as a pragmatic matter, honesty really is the best policy. But an honest person won’t be honest for this reason. I’m sure that’s true of you. It’s an ideal you value, not simply a calculation you make.

As you also understand, people who cheat exploit the good faith of those who don’t, because cheating lets them represent themselves as better than they are, relative to noncheaters.