nice ideas but the exercises are buggy. inadequate explanations for some, odd expectations for others. on some of the singing examples it is played in a lower register yet you need to sing up an octave to receive a checkmark. keep refining and making the user experience simpler and more rewarding. the provided exercises are suitable only for a beginner. I was looking for something to practice my interval and chord recognition for free daily, and this is more like a rudiments course.