Sound
Amplifying lectures, workshops & discussions
Sound is invisible until it fails, and then it is the only thing anyone can think about.
In a small room with good acoustics, you do not need amplification. In a large room, a room with hard surfaces, or a room where some participants are hard of hearing, you do, and standing at the front and speaking louder is not the same thing. A facilitator straining to be heard is tiring for everyone in the room.
If you are using a microphone, test it before the session: where it clips, how close it needs to be, whether it picks up rustling clothes or jewelry. If you are playing audio (a video clip, background music, a sound prompt), test the speaker volume in the actual room so you know whether it reaches the back.