For the record: Lehrer-style "new math" was what I was taught at elementary school in Ontario in the 1980s. I know it was not what my parents had been taught,

For the record: Lehrer-style "new math" was what I was taught at elementary school in Ontario in the 1980s. I know it was not what my parents had been taught, because they couldn't understand how we did subtraction. We did do some other bases (mainly binary, as I recall) as well as modulus. I certainly had unusually able teachers.