Suggestion--hide context tip by default
Just a quick suggestion -- when using flashcards, the context sentence is given at the top of the cards. This often makes it too easy, and is an irresistible temptation. It would be best if it was hidden, and the user had to click the field to reveal it.
Note that after you guess a flashcard’s meaning, all subsequent times the flashcard is shown will include the word you are trying to guess blanked out. So now you need to guess the word in your target language which is a bit more difficult.
The context is often necessary since it may affect the exact form of the word you are try to guess. e.g. in Spanish you may need the context to know whether an adjective applies to a male or female noun, and there are plenty of other examples.
The context can also affect the meaning of a word, e.g. in English “poker” can be a card game or a stick, and the context helps clarify this.
I do understand your complaint, but for the above reasons, I think that a context should always be visible.