Background
My wife is a private tutor and cannot carry on with classes due to Covid 19. Using Skype, Zoom etc is ruled out due to scheduling conflicts with schools using them. That pretty much left is with the only choice of recording videos, uploading them to cloud and sharing links with her students. Each video is typically half an hour
Set up
Room, isolated from external noise.
Whiteboard to draw and explain.
One Plus 7 mobile running Android 10 placed close enough and using the phone mic to capture audio.
Post recording processing on a laptop is not possible for a bunch of reasons. We don't want to invest in recorders, mixers etc
Problem
Ceiling Fan noise. It's summer here and a fan is a must (no air-conditioning). This makes for a poor video, especially when she is facing the whiteboard.
There is no problem with the video portion, lighting etc.
Tried and didn't work
She isn't comfortable with head phones, so I tried using Bluetooth earphones and using the Bluetooth audio instead of phone mic but it didn't work reliably.
Android apps that claim to reduce noise. Results aren't good.
These questions, emphasized that I should be using a good mic (since post recording processing is not possible)
Questions
What kind of mic and the typical characteristics of the mic I should be looking for?
Is there any other alternative solution apart from mic? For instance, a paid Android app that can do this for sure? Or something else?
We are on a budget and since the videos aren't meant to be high quality anyway, low cost solutions are preferred. It would be nice if someone could link a product from Amazon (India) as an example.
PS: Lengthy question, yes, to make sure the situation is clear and hoping for a workable solution