Challenge response time question:
I notice that when doing challenge quizzes that sometimes Sololearn pauses in the middle of the quiz for a brief period (could be sometimes as long as 10 seconds) after a certain question number and then recovers to continue with the remaining questions. This makes me think that the questions are loaded from the server to the App dynamically one by one. Can the protocol and the user experience not be improved if all 5 questions (and in the case of the challenge receiver, all 5 opponent responses as well) are loaded into the App at the start of the challenge? That way, any delays due to communications issues will only happen at the start or end of the quiz and not in the middle, which I find annoying.