Which sentence uses principal correctly? we learned the valuable principal of honesty from dad. our school principal is respected in the community. madame sofie taught her dancers the principals of ballet. responsibility is one of life’s fundamental principals.

The sentence that correctly uses the word "principal" is the second sentence. The word "principal" refers to the person who has the highest authority in an institution, particularly as referred here, which is a school. On the rest of the sentences, the right word to be used is "principle" and not principal.