App is frustrating. I have old and shaky hands, so make many typos on my phone. Have an android tablet, BUT, the app will not display properly on the horizontal screen with attached keyboard. I'm told it Used to work on such a setup. Correcting typos on my phone breaks my concentration on learning, and my progress is slower than it should be. There are also fairly frequent surprises when I'm fixing typos -- the app will act as though I've clicked the "Check" button, and mark my answers 'wrong'.