Duolingo has a free separate app with flash cards called Tinycards for easier memorization of lots of words. It’s currently just for iOS but they’re planning on expanding to Android soon.
So if you do well/better with flash cards for memorizing, get Tinycards. It’s been amazing for me to drill verb conjugations especially because there’s zillions of them, hahaha.
The original Duolingo is great for full sentences and sentence structure and all that but this is great for memorizing words to use in those sentences ;)