Further Readings
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/
Alternatively, you can attempt https://teachyourselfcs.com/ where it lists subjects you will encounter over the course of taking a Computer Science degree.
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.
This Codecademy course covers the basics of backend JavaScript servers that you would need to know to work with the internet, requests and handling data, like with the SQL language.