You don't have to use headphones or earphones in the SYNKii Classroom. But we strongly recommend that you do.
Wearing headphones or earphones will prevent unwanted echoes or feedback from disturbing your lessons.
Feedback is caused by the sound from your speakers getting picked up by your microphone, which can create a feedback loop.
We would suggest using wired sets rather than sets connected by Bluetooth, as this could increase the latency up to 500m/s.
Using a dedicated headset and microphone (laptop microphone or USB microphone) will give you the best experience in the SYNKii Classroom.