To avoid audio issues (feedback, echo), do not connect to audio when joining a Zoom session as a participant when in the same classroom the meeting is being hosted from. See the steps below.
Do not join Zoom audio on PC or Mac:
When joining a meeting, on the choose audio window select "X" on the upper-right corner.
Do not join Zoom audio on mobile device:
When joining a meeting, on the join audio pop-up window select No Audio.
Faculty: Zoom meeting hosts and co-hosts can utilize the Mute All button to prevent audio issues (feedback, echo, etc).