Hi @masterwriter. Even though this article is educational, it is quite long. I would suggest you break it into a few parts so that it will be convenient for your readers. You don't want to strain their eyes, did you?

For your pictures, I would suggest that, if your picture license is not CC0, write the name of the original author and also the license version along with the source. For example, your first picture can be written as:

Picture By CNX OpenStax - Wikimedia (CC BY 4.0)

The words are a little bit fuzzy but readable (If not, open it in the new tab). You need to provide the author name and license version.

Please note that I'm not in any way, try to disapprove your work. You've done an excellent job here, but you can make it better.