Just an idea:
I think that lesson 6 kind of stumbles a bit. We’ve been working in the internet simulator so far, we’ve built a network, we have data flowing across the network in packets, we can handle packets that are lost or out of order, and we can even deal with ip address changes. But when we get to http, the part that most people consider “the internet”, we watch a video and answer questions.
It would be wonderful if we could add just one more level up to the internet simulator. The last version adds dns servers. If (even in that same level) there were http servers, it would help show off the layers that we end up discussing. It could be something simple like the dns server, each http server responds to a GET request with some text. Students could be asked to get the “IP” address of the server from their DNS then get the answer to some question from the http server. It could even be a vocabulary server that responds with definitions for words requested.
That way students could see the answer to what happens when they type a url into the browser and press enter as was posed way back in lesson 2.1.