In Rules by Cynthia Lord what rules are important to Catherine?

Catherine's Rules:

Sometimes you've got to work with what you've got.

Say "excuse me" after you burp.

Don't stand in front of the TV when other people are watching it.

Flush!

You can yell on a playground but not during dinner.

A boy can take off his shirt to swim but not his shorts.

It's fine to hug mom. but not the clerk at the video store.

Sometimes people don't answer because they didn't hear you. Other times it's because they don't want to hear you.

If someone says 'hi', you say 'hi' back.

Catherine created her list of rules in order to teach David how the world works, as well as a way to not keep explaining things. She says that her parents have never explained these things to her, but rather, that she has always known them.