Lehrer is talking about "new math" from 60 years ago. (it consisted of talking about set theory, union and intersection, also mentioning commutative and distrib

Lehrer is talking about "new math" from 60 years ago. (it consisted of talking about set theory, union and intersection, also mentioning commutative and distributive princicples, i.e. mentioning some things that are not super necessary for arithmetic but which you will encounter later if you pursue mathematics further. In this way you would hopefully be more effective in contributing to the arms and space races and defeating communism.) https://en.wikipedia.org/wiki/New_Math https://en.wikipedia.org/wiki/New_Math not clear that GP is referring to the same thing at all, perhaps this https://www.parents.com/kids/education/math-and-science/new-math-method-explained-for-millennial-parents/ https://www.parents.com/kids/education/math-and-science/new-...