Aclass of third graders is told that the assistant principal will be visiting their class to confirm their teacher's reports of bad behavior. when the principal visits, the students behave perfectly. this is an example of

This is an example of "The Hawthorne Effect".

The Hawthorne effect which is likewise alluded to as the observer effect is a sort of reactivity in which people change a part of their conduct in light of their consciousness of being watched. Like in this case the students knew they are going to be observed so they modified their behavior.

we need an attachment to see what you are talking about.

the answer is implicit statements