You may find yourself in a situation where you need to start teaching on-line soon. If you are a classroom teacher who uses PowerPoint you are in luck! You can add audio content to your slides and then post the presentation for students. Here’s a demo video that walks you through the process of adding audio content to slides and two methods for saving your presentation to use.
Here’s a link to a list of inexpensive microphones that would be helpful for recording lectures. I use the SAMSON Go Mic USB at https://www.amazon.com/dp/B001R76D42 and it works well, but you may have better luck with one of these USB Microphones under $50