Unfortunately Google Meet does not have a built-in whiteboard tool. However, there are many excellent whiteboard tools that can be used with Google Meet. For example, two great Google tools that can be use as digital whiteboard in Meet are Google's Chrome Canvas and Google Jamboard.
To show how to use these tools, and specifically how to use them inside of a Google Meet for teaching as well as collaborating with students, I recorded a short 8-minute video. See below for the video and related resource links.
Tutorial Video (8 minutes)
Here is my quick 8-minute video on digital whiteboard tools you can use with Google Meet including Chrome Canvas and Google Jamboard.
Note: See all of my Google Meet help videos here:
Post by Eric Curts. Connect with me on Twitter at twitter.com/ericcurts