Maybe we don't learn everything we need to know in elementary school, but we sure learn a lot.
Never before was that clearer to me than today.
Without getting into specific situations or people (I don't want to call someone out in such a public forum), I will just say that children are sponges. They are observant and watch everything we do as adults, instructors, and mentors. In short, we need to model behavior we'd like to see.
So if we make a mistake as an adult, we need to correct it. If we offend someone accidentally, we need to apologize. We aren't perfect, but we need to strive to create a fun, safe, and stimulating environment for our charges.
Any moment can be a teachable moment. If, for example, there is garbage on the floor, and someone walks past it, we need to pick it up. We can use that moment to explain to our class what needs to happen with garbage on the ground. When students see the teacher or adult is picking up the garbage, they are that much more inclined to do it themselves.
Politeness, standard grammar/word usage, courtesy, inclusivity, and compassion are all things we should put forth in interactions with children. This is how they learn about the world - how to interact with other people. If we do not behave this way ourselves, we cannot expect such behavior of them.