Why did my hearts go away?
The 3 hearts that I get at the start of each lesson have disappeared. I would like to have them back because I feel that is the best way to learn. If I loose my hearts by answering wrong I need to repeat the lesson. Giving me unlimited chances does not help me to learn only to advance through the lessons without knowing what I am doing.
What you are describing is a new A/B test applied to many Duo users. In this test, when you go into a quiz you answer as many right until you a familiar with the information. If you get one wrong your progress will be set back. There is no way to loose which I think is more motivational than the sad Duo owl when you fail a lesson.