Hiragana Studying App

So I made a shitty app for android called Kana Quiz that's on the Amazon App store for studying hiragana it's really simple right now, but I'm currently working on an update that improves upon it a lot.  I'd really appreciate if anybody would be willing to check it out and give me some feedback.
http://www.amazon.com/Brynn-McCormick-Kana-Quiz/dp/B00DQC4Y06/ref=sr_1_1?s=mobile-apps&ie=UTF8&qid=1373252885&sr=1-1&keywords=kana+quiz&tag=thelinactsho-20

I don't have adroid so I can't test yours, but I got the idea from the images... I made one for w8, it's pretty crapy though.
http://apps.microsoft.com/windows/app/hiragana-katakana-trainer/bd181abd-d917-4db9-91ee-2420b302f67c