Your daughter and mine would get along famously it sounds like. The funny part of the escapade was that I had explained to my daughter about the boiling points of water and alcohol. She then told the teacher what I'd said. Teacher did not believe her.
Sometimes I don't talk so polite when people are stupid. Teacher argued with me. I told her how the cow ate the cabbage. She was a neighbor to one of my uncles who had taught biology at the high school and gone on to be school principal. I called him in on the discussion, not very nicely, and had him confirm my story. Teacher thought I was a dumb hick. Sometimes I am also not remorseful that I have spoken impolitely to people.
You just have to do in in such a way that they are thinking it is a compliment - yet gets a dig in that is over their heads -but others listening get the point. It isn't really that hard with most 'liberals'. But you are right - we have to take a firm stand or they feed on their own ignorance.