Years ago I was tasked with building our first cloud networks and no on-premises resources were available to help us design our cloud address space. I learned how to do subnetting using a the "davidc" tool you'll find online, which I absolutely love.
Now I help and coach customers designing networks and decided to re-make the tool with a more collaborative mindset. While it's not a learning tool, I think this will help people visually understand how it works in the real world. If you click around the join/split options you'll see what the numbers mean in practice and that should enhance any academic/binary understanding.
Animated Demo - https://raw.githubusercontent.com/ckabalan/visualsubnetcalc/...
There is no database or back-end; it's all in the browser and generates links/exports for users to share.