I’ve been working my way through Code.org’s CS Principles widgets and having a terrific time. There has been some great thought and originality put into the design and implementation of the individual widget.
I’ve worked my way down to the Internet Simulator.
If you’re interested, you’ll undoubtedly be advised to read the lesson plans first. These not simple activities without some background and understanding but then the internet isn’t a simple thing to begin with!
This is a great simulator to gets hands on and learn about internet communications.
If you’re teaching the concepts, you’ll definitely want to add this to your toolkit.