'16-'17 General Discussion for Lesson 1.3

Use this thread to discuss your questions and comments about how to run the lesson.

Last year there was a video guide to go with the Wires movie. It’s not in this year’s curriculum. Is there a reason? I really like having video guides with the films.

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Ditto. I was showing the video today, remembered it from last year and realized I didn’t make copies for it .

thanks for flagging, @cmeeks. i added it in under resources.


I found it under Lesson 5.

it was part of lesson 5 last year, but as of last night it’s also part of current unit 1 lesson 3, here

With the multiple choice questions in code studio, do students have unlimited chances to get the right answer and if so can that be changed so we can use it as a graded assignment for correctness

hi, @bbinkley!

there are two different types of multiple choice assessment questions in code studio-- the questions that are integrated into each lesson (which we’ve designed for formative assessment) that take the form of bubbles at the end of the lesson stage and the locked assessments that cover each chapter of the unit (which we’ve designed to mirror AP-style questions, and can be used as summative assessments for the lessons they cover):

because we made the first set of questions for formative assessment and many people structure and use formative assessments in very different ways, we don’t want to lock them down and require students get the questions correct the first time around. and don’t forget that you’re always welcome to take and use these questions outside of code studio if you want to capture correctness.

hope this helps!


When I looked at this last week I saw a video going over how to give the Flashlight signal lecture. This morning I’m looking for it and can’t find it?

i’m not familiar with the video you’re talking about, but there’s a google presentation you can use that’s in the “links” section on the right side of the lesson:

Hi All,

I just finished this lesson today. Students get so engaged in the tools, it’s awesome. Now that this is my second time through, I am intentionally planning on more extensions so students who are “done” can get additional challenges. I even had some students try to send text based messages in this lesson which tells me their heads are in the right spot!

I also continue to love the videos. This video in particular was really well done!

I do wish I had a better way to distinguish between latency and bandwidth for students. Does anyone have any good metaphors to make these two concepts a little more “sticky” for students?


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Latency and bandwidth are related.

Bandwidth is a measure of potential - the transmission capacity.
Latency is a measure of delay - the amount of time it takes to get from sender to receiver.

“Throughput” is another term that’s related, that I believe has to do with the actual amount of data getting through, as opposed to bandwidth which is more of a measure of potential. i.e just because you claim to have say 1GB bandwidth doesn’t mean you’re actually experiencing it.).

Here are several explanations that I’ve heard over the years:

  1. If it’s plumbing: bandwidth is the diameter of the pipe, latency is how long it takes a drop of water to get from one end of the pipe to the other. So in other words, your faucet might have a lot of water pressure (high bandwidth), but when you turn the faucet on, do you have to wait a few seconds for the first drops to get there (high latency)? It’s worth pointing out that just because you have big pipes doesn’t mean you use them to their full capacity all the time.

  2. “never underestimate the bandwidth of a station wagon full of [hard drives] hurtling down the highway” - Andrew Tanenbaum. This quote is from a classic book on networks in which tanenbaum is contemplating the fastest way to send massive amounts of information from one side of the country to the other. If you fill a station wagon full of hard drives you could potentially send petabytes of information from los angeles to new york in a matter of days. Of course, it takes a few days for the first bit to get there (high latency) :). But once the first bit is there, the last bit is too. By contrast if you sent the same data over a network, the first bit might get there in a matter of seconds, but depending on the network speed, it might still take the last bit a few days to get there.

check my math:
1 petabyte = 1x10^15 bytes
1 gigabyte = 1x10^9 bytes

So assume you had a pretty fast internet connection, say 1GB / sec - this is a measure of bandwidth - with basically no latency so when you send a bit it gets to the other end almost instantly.

Then to send 1 petabyte from LA to NYC at 1GB/sec would take 1,000,000 seconds == 11.5 days.

If my station wagon with 1PB of data on hard drives would take, say 5 days to drive from LA to to NYC, then my station wagon has an effective bandwidth of 2.3GB/sec more than double your fast internet connection, despite the high amount of latency.

That help?



I completed this lesson yesterday. The flashlight PowerPoint was an excellent addition to the course. I spent some time on the definition of a protocol. My students quickly discovered that internet sim was almost impossible to use. They were able to meet the goals of the lesson although I wish they had a little more time to practice and perfect thier protocols. I gave them the Wires, Cable and WIFI and extended learning for homework. I will reinforce the vocabulary words tomorrow.

Can someone give a example of a successful 2-bit message relay? Still not understanding how to send a multi-bit message if the shared wire can only be in one state.

The two people must agree on a pulse rate and set it to the same value on each of their widgets. They must also agree on when the sender will write on the wire and when the receiver will read the wire. Suppose the pulse rate is set to 2 seconds per pulse and sender will send within the first pulse (that is within the first 2 second interval) and the receiver will read in the next pulse (within the the next 2 second interval) and then alternate writing and reading in every pulse (2 seconds). If the message to be sent is ABAB, the image below shows the pulse count and the time interval during which the wire is written to or read from.

I hope this helps!


Thank you. That does help.

Is bit rate calculated only for the time it takes to set and read one message, or for that message to make a round trip?

The activity guide says “A bit rate is a measure of how fast a system transmits bits. You can calculate your protocol’s bit rate by dividing the number of bits sent by the amount of time it takes. Calculate your bit rate for one of your fastest runs of your protocol. Note: If you send 4 bits back and forth, you’ve actually transmitted 8 bits.”

Bit rate is the number of bits sent per second. In the example, I am sending 1 bit every 2 seconds. So the bit rate is 1 bit/2 seconds or 0.5 bits per second.


New to this forum, sorry if didn’t see answer elsewhere. Am trying to connect to the internet simulator just to try it out (realize need a partner to really use it), but the url code.org/internetsimulator in the instructions just seems to go back to the curriculum, not a page of configuration option or a lobby. Any suggestions?

To play with the internet simulator just open the internet simulator in two windows and you will see two of you (ex. john and john1) and you should be able to connect and play around but you will need to switch windows. I hope this helps.

Please provide the link to the instructions where it seems to be taking you back to the curriculum so someone at code.org can take a look at it.