How can I tell, as a teacher, whether the students have disengaged their microphone or not?
You cannot tell on your end. Can you please explain more about why it would be useful so we can pass it on to the development team? We offer four different platforms (web/ios/android/windows), would you like one in particular? It can be tricky because of situations where students turn the microphone off on one platform but not the other, but this may be worth considering. :]
For now, you could ask students to do exercises in front of you, or show their settings to you once in a while.
Thanks for your response! Each time we begin, I tell them to make sure that they have their microphones engaged. The reason for this is because, as a teacher, I would like to make sure that they are also learning to speak the language. Additionally, many times, the students will work on Duolingo at home. The report may tell me that they have completed x amout of xps; but they can also accomplish those xps without speaking. Most of them would prefer not to speak the new language, but that would not be as helpful to them in the long run. Thanks again!