In my experience as a maths teach I always came across one or two people in a class who had the courage to object when I mentioned that a "square IS a rectangle".
In my early years a quickly laid the law down and got on with the more important part of the lesson. By doing this I probably lost the loyal support of a diligent and enquiring pupil. With more experience I realized that there was a golden opportunity to hone my mediation or negotiation skills, and keep an enquiring mind happy, educate the rest of the class in good manners, and all this without any great interruption to the subject in hand.
