If you are a Mac user, and if you want to use a whiteboard software in your class or if you want to screencast your lectures, then you can choose among the three whiteboard software below. The first two are free and the third one has a free version.
3 Free Whiteboard Software for Mac Users
Not many people use it, but Paint for Mac is a very useful software. It is a Mac equivalent Paint in Windows. I was using Paint before I migrated to Mac and I’m still using it often particularly in simple image editing particularly cropping. Paint can also be used as a whiteboard software. I myself have used it many times.
BaiBoard is another whiteboard software with collaborative capabilities. When it comes to texture, it is better than Paint. However, its downside is its drop down color palette. If you are doing a screencast, it is slower to change color.
Autodesk Sketchbook has a lot of more features than the two whiteboard software mentioned above. As the name implies, it is used for sketching and drawing, so it has a variety of brushes. Although its feature is not really as a whiteboard, it can still be used for such purpose.