This is a great app, if you are native English speakers. I took Korean lesson, and it's only available in english. Basic levels are easy, now I'm on first checkpoints and I gave so many wrong answers because of my English grammar limitations (forgetting to use a/the, wrongly use do/does, etc). I ended up memorize some answers, instead of trying to understand the Korean grammar. I hope the app is not too strick on following the english grammar, because I use it to learn Korean, not English.