This could be a big topic and a lot of writing, but I will make it short and simply suggest what I use.
For delivering virtual courses, that is, live Internet deliveries, we need to use a mic and some way to control it. In most delivery platforms like Adobe Connect, it will use the local plugged in mic and you control the volume with its audio wizard.
But has anyone listened to the sound that a student hears? Many trainers have never listened at the student side. If they did, they would throw away a desktop mic, room mic or conference phone. The echo, low sound and low quality sound is irritating when a student has to endure 6 hours of instruction. Might be fine for that one hour WebEx session. We put up with laptop speakers and tiny mics.
Here is what I use for my studio and for the mobile classroom. (the mobile classroom is any classroom where I am asked to deliver virtual, or live students plus virtual and I bring my equipment with me). I use this setup for recording how-to videos too.
Get a Good "clip mic". These small mics clip onto your tie or button-line of your shirt. They are close enough to your mouth without being in the way and they are consistent, as they let you move your body without the mic staying behind. Don't clip it to one side only or a collar. When you head moves, the sound dimishes. Keep it center along your shirt button line about 2 or 3 buttons down.
My clip mic connects to a wireless transmitter that you put in your pocket or clip to your belt. Total freedom to move around. The receiver is a small black box near your computer or mixer where the sound will go. I use a small inexpensive mixer that you can carrry around with you. The output from the mixer goes to your PC as a USB input or even old school line out and in. This may sound like overkill, but the sound is amazing and students comment on it (good things). The mixer has a mic preamp, treble and bass adjustments, panning (move your mic to left or right or center), reverb, recording out, line out and other functions you may not use. It also has line inputs to bring in or "mix" other sound sources... computers, CD players, iPhones and other sound sources.
For the mic system, I use the Shure BLX Wireless Presenter which has the clip mic and the receiver pair. $150 to $250. These used to be $1000. You can also use a hand-held mic with these recievers but that would be for singing....
For the mixer, I use the great quality but inexpensive XENYX line of mixers, thanks to CTE Solutions for using them in their classrooms and proving their value. I use a 2 mic/10 input QX1002USB but for portable use or first time trainers, use the QX502 or 302. The 302 has only one mic input and room for line inputs if you need them. That should be enough. I saw a 302 at Long and McQuaid for $87.00
Regardless of the mixer, keep it simple and get to know how to use it. For example, one classroom I was in had the reverb up to 75 (that orange display you see) and no one knew what was causing it. (should be zero for speaking). We only use reverb if we want to break out in song... and we shouldn't! Make sure you get a USB version of a mixer so you can easily hook it up to your computer... any computer and get broadcasting.
I will write more later on how to use a mixer properly. It can be very easy for the non sound engineer like most of us. We just want a great delivery without the ugly sound or ugly video quality.
I'll take care of that so you can focus on teaching. Tune back for the next post.