I’d say ‘The maths curriculum is ineffective’ as both ‘maths’ and ‘mathematics’ are not the plural of anything just as ‘physics’ is not the plural of ‘physic’.
‘Two plus two is four’ once again because although the words two and four represent numbers higher than one, they are not plural.
One cannot define absolutely one version of English to be more authentic than another, but English written the English way by the English people who invented the English language in England has a reasonably good call on being the original! :)
Thank you again for your scholarly erudtion. I do cede your point that proper English came from the English - lol. We sure have made a botch of it. I love to hear you guys speak. Your accent alone makes you sound intellectually superior. With Wales-speak being the exception - lol. I take pity on the road sign makers there.
And there are no better sitcoms than Brit sitcoms which we steal regularly. Allo Allo being the hands down sidesplitter.
I was just curious about a grammatical practice that piqued my interest when traversing your fine land. My harassment ARE now terminated. Thank you very much and God Save the Queen and all that.