why are thr rules important to catheran

One of the nice thematic concerns of the novel is that Catherine has also developed rules for herself. One important rule is "No dancing unless I'm alone in my room or it's pitch-black dark." This rule displays Catherine's shyness and her unwillingness to take chances or embarrass herself. And this fear of embarrassment is precisely what motivated her making of David's rules. In the end, Catherine must break her rule by dancing with Jason at the community center dance. By breaking the rule, Catherine shows that she is no longer motivated by the fear of embarrassment. And in the last scene, Catherine only laughs when David reminds her of the rule about no toys in the fish tank. She has learned to live with her brother's condition, and to no longer try to confine him with society's rules.

The rules help her eight year old brother David to reduse chances of embarrassment or something bad to happen,plus David likes rules.Catherine makes rules for herself too like:No dancing unless im alone in my room or its pitch black dark.