From Wikipedia: The word mathematics comes from the Greek μάθημα (máthēma), which, in the ancient Greek language, means "that which is learnt", "what one gets to know", hence also "study" and "science", and in modern Greek just "lesson".
Math derives from the word μάθε?
Ancient Greek ‹μαθειν› (to learn, μάθω) → Ancient Greek ‹μαθηματηκή τέχνη› (mathematical/learning art) → Latin ‘Ars Mathematica’ (mathematical art) → English Mathematics
Source: Google dictionary
look up the word "polymath". It means someone who knows everything.
"Study Greek!" is not good?
Greek has different words for "learn" and "study", just like English: learn -> μαθαίνω, study -> μελετώ. Hence "Study Greek," would be "Μελέτα ελληνικά."
Sometimes in different lessons the words for languages are capitalised and sometimes not. Which is correct?
Imperfective imperative= μάθαινε / μαθαίνετε. Perfective imperative = μάθε / μάθετε