Khan Academy also has some fun lessons that are more focused around programming concepts and fun things to build.
For a broader Computer Science overview of the field, Harvard's CS50 is a good choice. This course is quite a bit more difficult than Fundamentals and uses the C programming language, among others.
You can take the course through a MOOC (Massive Open Online Course) at EdX: https://www.edx.org/course/introduction-computer-science-harvardx-cs50x or, use the course materials separately: https://cs50.harvard.edu/
If you're interested in how real-world software systems are built you can begin to learn about a modern set of libraries and tools you'd need to do that.
This Codecademy course is the closest to the material we've already covered that will show you how modern Front-end apps are built: https://www.codecademy.com/learn/paths/front-end-engineer-career-path Note: Front-end here, refers to the browser, where we ran all of the code in Fundamentals.