This page would be 100x more effective if figure 1 filled the layout width (on desktop).

CMapTools (the software made by ihmc.us) is one of the best tools for creating concept maps. Nice to see cmaps explained well.

If you're interested in seeing some examples, you can check out the following cmaps from my books:

High School math (a.k.a. precaluclus): https://minireference.com/static/conceptmaps/math_concepts.p...

HS math, MECH and CALC: https://minireference.com/static/conceptmaps/math_and_physic...

LINEAR ALGEBRA: https://minireference.com/static/conceptmaps/linear_algebra_...