Second Grade Intellectual Development
They have a sense of justice.
Although it’s common for kids to complain that something’s unfair or someone’s cheating, kids this age are developing a legitimate understanding of fair and unfair. This is an important distinction, but it doesn’t put a stop to the complaining.
What you should do: When your kid complains, ask questions. Give her a chance to articulate her opinion. Who knows? She might actually be right!