There's no language I'd want to teach (applied) math in more than Julia. Lean is obviously kind for anything involving a proof, but for teaching anything with linear algebra involved the syntax alone is enough of a reason to prefer Julia.
Optimization, specifically the kind that JuMP tackles, is another field where teaching is probably easier in Julia than any other language
Optimization, specifically the kind that JuMP tackles, is another field where teaching is probably easier in Julia than any other language