Lithuanian is not a Finno-Ugric language, but a Baltic one. Perhaps you are thinking of Estonian?

Personally I think using the metric system is more important for learning science than the instruction language. When you get down to it, the "simple Finnish words" are just as alien to everyday life as the Latino-Greek words. A word like "jännite" does not confer any more insight than "voltage". In advanced topics Finnish also uses loan words for things like electrons, momentum, grammatical cases and so on.