Thursday, September 14, 2017

Be a Router and Share Messages

The curriculum I am using for Advanced Placement Computer Science Principles is the excellent Code.Org curriculum. I really like the Internet Simulator that is involved in many of the early lesson in the Internet unit. It really lets students try a lot of things. I like to add a bit of my own flavor though and involving physical objects and activities is part of that. So today I had my students send messages through routers where students played that part of routers.

Here’s what I did. I semi-randomly assigned each student a two part address. The first number indicated a router and the second a student “connected” to that router. I randomly assigned a students to be routers. I selected the number of routers based on the number of students in the section. I think you need at least two routers but more would be better if the class size allows it.

imageI prepared a bunch of “message packets.” and handed a couple of them to each student who was not a router.

A list of students with their “IP addresses” was displayed on the board. I could have printed them out if I liked wasting paper but I don’t.

Students were to write out a question in the message field as well as the send to and return addresses (the codes I had created) and send the message. They were to give the message to the “router” they were connected to. The router was then responsible for either handing the message directly to the intended recipient if they were “on the same router” or pass it along to the appropriate router if not. That router was responsible for passing it to the recipient connected to them.

After a bunch of messages and replies were sent we discussed what happened. Some good things happened. Well bad things depending on how you want to look at them. I love learning moments so they were good from my point of view.

One router was overwhelmed with messages and took a while to get them all to the right place. Great! Bottleneck simulated!

Some addresses were not well written and could not be delivered. I may send some messages like that myself next time to make sure that happens. Dropped message and what that means for the learning experience!

I did this with minimal discussion first so that students didn’t know exactly what to expect. I’m hopeful this made the later discussion and the exercise with the Internet Simulator.

What do you think? Look reasonable to you? What do you do to help students understand routers and what they do?

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