In order to make the transition working from home as smooth as possible for both the teachers and the students. We have collaboratively come up with a solution to provide a method of using your cellphone as an overhead camera for solving equations and sharing them with the students via video. Using this solution with a Mac computer requires your android phone be on WiFi.
Android with Linux/Windows/Mac.
Free WiFi based application for using the camera on your phone and accessing it from within your web-browser. Simply search for the app within the android play store. The icon for the android store looks like this.
After launching the app on your phone you will be asked to grant permissions to the app to record and take photos and videos.
Once the app is installed and you have granted the proper permissions. Assuming your device is on wifi, you will be presented with your device ip address and a port. Type this info into your favorite web browser and you will be able to see your phone camera on the website. If the image is smaller than desired zoom in on the webpage.
There are some settings available, such as to use the microphone on the phone (off by default) and changing between the front and rear camera (rear camera is enabled by default). These settings are accessible via the 3 vertical dots in the top right corner.
If you do not have wifi at home and would like to use this feature. Another option exists by using usb tethering. This will emulate a network connection between your computer and the phone over a usb cable. To do this on android 10 go to settings, network & internet, Hotspot & tethering, and then selecting USB tethering. Once that option is enabled, open the app, and follow the steps described above. (This option does not use your personal phone data connection)
Once you have DroidCam working with your computer you can setup a document camera with a simple setup like mentioned in Stand Alone Document Camera document.
Here is a quick example I made. I used my android, a pair of chopsticks, my speaker, and marble coasters for weights.
In the above picture I used Zoom on my laptop camera so I could capture both the image from the Android Camer via DroidCam and the document camera setup I had made.