Learning German I'd write flashcards with summer on the front and der Sommer on the back. However, learning Italian, the back would say l'estate, with no way to tell whether the word is masculine or feminine. Is there a good way of solving this problem that I haven't thought of?
Of course I could write estate (f), but it adds a step in the thought process and feels unnatural. I could also write la estate but maybe that would even be detrimental to my Italian.
You might add to every flashcard an example of the word in use (which is useful independently of the gender determination) – a proverb, or a poetic line, or a quotation including it, say, perhaps from Wikiquote – taking care, for a noun, that in the sentence an unambiguous article or an adjective is apposed to it.
Add the symbols ♂ and ♀ to the flash card? Or you can use different colors like pink and blue but that might became too laborious. I think the brain would automatically pick those up without any extra thinking.
You could use the indefinite article. Un ' estate :) I think it's the best trade-off, considering that you will be able to learn when to use effectively apostrophes (a bad grammar mistake if you want to write correctly).
