Duolingo adds new language exercises and revamps its leveling system

Duolingo today launched one of its biggest updates in recent years. The company is introducing a range of new exercise types, as well as a new leveling system that lets you choose between delving deeper into specific skills or learning new content.
When you are building a popular language learning service like Duolingo,you’re inevitably confronted with a problem: Some of your users are really serious about learning a new language and some are just casual users. Finding a balance is hard, e