In building this app, we didn't survey the research addressing that question specifically (though googling "L1 vs L2 flashcards" pulls up some interesting sites).
For me personally, speaking from 15+ years learning French, Chinese, and Turkish, it's native --> target. Learning that way helps me recall faster when I need to construct my own sentences. If you're looking just to learn to read, I think target --> native is easier and might be a better approach.
I've also had success starting with native --> target to familiarize myself with the word, then quickly switching to target --> native to solidify my ability to produce it on my own.
In building this app, we didn't survey the research addressing that question specifically (though googling "L1 vs L2 flashcards" pulls up some interesting sites).
For me personally, speaking from 15+ years learning French, Chinese, and Turkish, it's native --> target. Learning that way helps me recall faster when I need to construct my own sentences. If you're looking just to learn to read, I think target --> native is easier and might be a better approach.
I've also had success starting with native --> target to familiarize myself with the word, then quickly switching to target --> native to solidify my ability to produce it on my own.