I'd second all of Sangeeta's suggestions. As she mentioned, the key takeaways are
- Computers online communicate using a protocol called HTTP
- HTTP is done entirely in ASCII and just assumes that all the systems students learned throughout this unit are working and will take care of actually breaking apart the message into packets, routing the packets, and delivering them to the intended recipient. HTTP relies on those systems working but doesn't care how they do it. This is an example of abstraction.
Don't forget that we've got some great videos to help you and your students visualize how these systems work. This one The Internet: HTTP and HTML gives an overview of how HTTP works. The developer tools are just another way of seeing this protocol in action, but in an interactive way.
Let us know if that helps!