I have not used it personally (and am not affiliated) but I've heard good things about ALEKS. It provides an adaptive learning path that supposedly adjusts to you as you master topics. Now that I think about it I think Kahn academy might have a similar feature. For personal use ALEKS has a subscription plan that provides access to their whole catalogue.
This system is used to classify colleges and universities into some thirty plus categories based on student population, degree type, and broad area of study. There is a PDF flowchart that explains the classifications: [PDF] http://carnegieclassifications.iu.edu/downloads/CCIHE2015-Fl...
I came across this on The Research and Education Networking Information Sharing and Analysis Center (REN-ISAC)'s site as a method of calculating membership fees as a function of institution size. https://www.ren-isac.net/membership/fees.html
In anyone was wondering how to quick toggle grayscale on android. I came across a couple of articles on breaking phone addiction by using a grayscale filter awhile back, but couldn't figure out how to toggle it quickly in Android. This app (not affiliated) is able to after granting secure settings permission via ADB. Pretty happy so far.
https://www.aleks.com/independent