Tone is all about reading the room. Duolingo's voice will always stay the same, but we adapt the tone to the audience's state of mind. The right tone takes judgment. Think about how the audience may be feeling, then write to that feeling with empathy. Regardless of the subject matter or situation, always strive to be clear, human, and relaxed.
Content
Since language is such a huge concept that everyone can relate to, Duolingo content runs the gamut. Sometimes we'll share funny pop-culture references. Sometimes we'll share content that's much more serious. This content can coexist if we're careful about tone.
Context
The Duolingo app is full of positive and negative moments. It's important to watch our tone as learners navigate them.