"HOW DO I MAKE IT SO THERES NO STRANGE AGE GAP" they could be co-teaching and one of them is just a little bit more clueless about maths because it wasn't their primary subject when attending uni for teaching. they could teach at a bilingual school where some subjects are taught in both English and some other language (this could also lead to jargon banter à la "can't think of the English expression" and "why the fuck would you call it that in [language] that just sounds wrong)

OMG YES ANON………YES…..FRENCH LOUIS….R I S E

“quick maths tomlinson–if jean valjean had 60 candies and and javert gave him 20 candies for valentine’s, how many bonbons does jean valjean have in total?”

“uh…………soixante bonbons, et vingt bonbons font…….quatre-vingt!!! four-twenty!!!! HA! TAKE THAT ‘ARRI!”

“…four-twenty…?”

“……..EIGHTY, I MEAN EIGHTY”