Acknowledgement to Katie Wardrobe, Midnight Music, for this excellent guide to getting the best audio in a Zoom music lesson:
https://midnightmusic.com.au/tag/zoom/
This site has info for iPhones and Android phones:
Microphones
Using an external microphone for your computer greatly improves the sound at my end and this makes for a better music lesson.
Recommended USB microphones:
Blue Snowball
Blue Yeti
Recommended microphone/recorder:
H2N Zoom