Why did you introduce the word "Kontra" as though it were a general noun meaning "coupterpoint"? All my sources treat it as either a preposition ("against" or "versus"), or part of a compound noun, as in "Kontrapunkt". It hardly fits in with the basic exercises. It made no kind of sense in the sentence where it was used.
The word actually exists as a noun in German. It is derived from the card game 'Skat' where it is used to double the points on stake for a game after your opponent has announced the kind of game being played (see the rules of Skat if this sounds obscure..) and you're quite sure you're going to beat him. It's also used metaphorically in the sense of 'to flatly contradict sb.'. But I certainly agree that this is not the kind of vocabulary you should give to beginners (or even intermediate learners).