Today in second grade, two of our 'robust' (fancy name for vocabulary) words were 'rare' and 'common'. The teacher explained that common things happened every day, rare things happened only once in a while. She asked for examples from the children and hands went up.
It went from "Playing video games is common" to several "seeing my mom (or dad) is rare". :(
It is often suddenly sobering when you open discussions with second graders.