"For Nick McIvor, a maths teacher at St Marylebone Church of England girls’ school in central London, there is no such thing as an average day at work."
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"When Alec Fanaroff of Potomac, Maryland, looks back at his fifth-grade school year, one memory stands out. His math teacher routinely handed out candy at the end of class to students who answered questions correctly."
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Does that mean that in British English we write a maths teacher while in American English we write a math teacher? Dictionary says that "mathematics noun [U] (UK informal maths , US informal math) formal."
Yes, that's correct. We call it "math" in the US.