From 68f3ea7aa7bc45cf75309f05b8f8b1f992841c03 Mon Sep 17 00:00:00 2001 From: Michael Ball Date: Wed, 25 Sep 2024 16:12:35 -0700 Subject: [PATCH] a11y: sigh, why isnt this page passing the heading order test? --- .../lab-pages/1-reliable-communication.html | 483 +++++++++++------- 1 file changed, 287 insertions(+), 196 deletions(-) diff --git a/cur/teaching-guide/U4/lab-pages/1-reliable-communication.html b/cur/teaching-guide/U4/lab-pages/1-reliable-communication.html index f1b4d5e29..cfd9c4456 100644 --- a/cur/teaching-guide/U4/lab-pages/1-reliable-communication.html +++ b/cur/teaching-guide/U4/lab-pages/1-reliable-communication.html @@ -1,214 +1,305 @@ - - - - Unit 4 Lab 1 Teacher Guide - - -

Lab 1: Computer Networks

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KEEP SUCH THAT needs to be fixed. --MF, 6/22/20
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This lab offers a very brief overview of what could be (and often is, in college-level CS) a full course in itself: how the Internet works. It emphasizes a few key ideas:

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In addition to these main points, there's a lot of vocabulary the College Board expects students to learn. We try to present the vocabulary a little at a time, in contexts in which each term makes sense.

+ + + + Unit 4 Lab 1 Teacher Guide + + +

Lab 1: Computer Networks

+
KEEP SUCH THAT needs to be fixed. --MF, 6/22/20
+

This lab offers a very brief overview of what could be (and often is, in college-level CS) a full course in + itself: how the Internet works. It emphasizes a few key ideas:

+ +

In addition to these main points, there's a lot of vocabulary the College Board expects students to learn. We try + to present the vocabulary a little at a time, in contexts in which each term makes sense.

-

Pacing

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- The 4 lab pages could be split across 2–4 days (80–160 minutes). Expected times to complete follow: - -
+

Pacing

+
+ The 4 lab pages could be split across 2–4 days (80–160 minutes). Expected times to + complete follow: + +
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Lab Pages

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Are we cutting these assignments? If so, please delete HTML. --MF, 5/16/20
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Solutions

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Correlation with 2020 AP CS Principles Framework 

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Computational Thinking Practices: Skills

+ +
  • + Tips:
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    • 1.D: Evaluate solution options.
      • -
    • 5.A: Explain how computing systems work.
      • +
    • Ask your school's IT person if you can run "traceroute" in class, to show + students how a message is routed to a computer in another country.
    -

    Learning Objectives:

    +
    • + + +
  • + Page 2: Network Redundancy. +
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    • Learning Goal: Understand how network redundancy is accomplished on the + Internet.
      • +
    • + Tips:
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      • CSN-1.A: Explain how computing devices work together in a network. (5.A)
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      • CSN-1.B: Explain how the Internet works. (5.A)
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      • CSN-1.D: Describe the differences between the Internet and the World Wide Web. (5.A)
        • -
      • - CSN-1.E: For fault-tolerant systems, like the Internet: -
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        1. Describe the benefits of fault tolerance. (1.D)
          2. -
        2. Explain how a given system is fault-tolerant. (5.A)
          3. -
        3. Identify vulnerabilities to failure in a system. (1.D)
          4. -
        -
        • +
      • + After students have worked through the questions on the lab page, you could use these + questions for a group discussion: + A network with the sender connected to the receiver via a multitude of nodes and routes demonstrating network redundancy +
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        • Are there any other two nodes whose failure would stop the message from going + through? Either the two neighbor nodes of the receiver could fail or the right + neighbor node of the receiver and the node above the left neighbor node + of the receiver could fail.
          • +
        • What is the minimum number of extra connections you'd have to add so that + any two nodes could fail without preventing messages between any two + other nodes? The answer is two. There are four vertices with only two neighbors; + use one edge to connect any two of those, and another to connect the other two. + (This will require "crossing" connections on the graph as it is drawn here, but + this is OK and could offer an opportunity to remind students of what the + elements of the graph represent.)
          • +
        • What is the minimum number of nodes that can stop working before the + sender and the receiver can't communicate? One way to answer this question is to + note that the receiver has only two neighbors, so if those two nodes go down, it + can't get any messages no matter where the sender is in the network. (The same + argument applies to the sender, but since the sender has three neighbors and 3 + > 2, it's the receiver that provides the answer to this question.)
          • +
        • What is the maximum number of nodes that can fail and still let Sender + and Receiver communicate? To answer this question, you can find the shortest + path between the desired endpoints (which is the one through the two + highly-connected central nodes) and then let all the other nodes fail.
          • +
        +
        This is new. I pulled it off the bottom of the student page and + dumped it here. --MF, 11/18/19
        +
        • +
      • The last question on this student page poses several questions. Here are some possible + correct responses: +
          +
        • The benefit of fault tolerance is that if some piece of the system fails, the + whole system doesn't fail.
          • +
        • The Internet is fault tolerance because is has redundant connections.
          • +
        • The vulnerabilities to failure include damage to a cable, power failure, + military intervention, hardware malfunction, etc.
          • +
        +
      -

      Essential Knowledge:

      +
      • +
    +
    • +
  • + Page 3: Internet Abstractions and Open Protocols. +
      +
    • + Learning Goals: +
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      • Understand the four layers of abstraction in the Internet protocols.
        • +
      • Understand how TCP/IP together provide the main abstractions for the net.
        • +
      • Understand how your home router can send a message to any IP address.
        • +
      +
      • +
    • + Tips:
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      • CSN-1.A.1: A computing device is a physical artifact that can run a program. Some examples include computers, tablets, servers, routers, and smart sensors.
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      • CSN-1.A.2: A computing system is a group of computing devices and programs working together for a common purpose.
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      • CSN-1.A.3: A computer network is a group of interconnected computing devices capable of sending or receiving data.
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      • CSN-1.A.4: A computer network is a type of a computing system.
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      • CSN-1.A.5: A path between two computing devices on a computer network (a sender and a receiver) is a sequence of directly connected computing devices that begins at the sender and ends at the receiver.
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      • CSN-1.A.6: Routing is the process of finding a path from sender to receiver.
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      • CSN-1.A.7: The bandwidth of a computer network is the maximum amount of data that can be sent in a fixed amount of time.
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      • CSN-1.A.8: Bandwidth is usually measured in bits per second.
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      • CSN-1.B.1: The Internet is a computer network consisting of interconnected networks that use standardized, open (nonproprietary) communication protocols.
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      • CSN-1.B.2: Access to the Internet depends on the ability to connect a computing device to an Internet-connected device.
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      • CSN-1.B.3: A protocol is an agreed-upon set of rules that specify the behavior of a system.
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      • CSN-1.B.4: The protocols used in the Internet are open, which allows users to easily connect additional computing devices to the Internet.
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      • CSN-1.B.5: Routing on the Internet is usually dynamic; it is not specified in advance.
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      • CSN-1.B.6: The scalability of a system is the capacity for the system to change in size and scale to meet new demands.
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      • CSN-1.B.7: The Internet was designed to be scalable.
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      • CSN-1.C.1: Information is passed through the Internet as a data stream. Data streams contain chunks of data, which are encapsulated in packets.
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      • CSN-1.C.2: Packets contain a chunk of data and metadata used for routing the packet between the origin and the destination on the Internet, as well as for data reassembly.
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      • CSN-1.C.3: Packets may arrive at the destination in order, out of order, or not at all.
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      • CSN-1.C-4: IP, TCP, and UDP are common protocols used on the Internet.
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      • CSN-1.D.1: The World Wide Web is a system of linked pages, programs, and files.
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      • CSN-1.D.2: HTTP is a protocol used by the World Wide Web.
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      • CSN-1.D.3: The World Wide Web uses the Internet.
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      • CSN-1.E.1: The Internet has been engineered to be fault-tolerant, with abstractions for routing and transmitting data.
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      • CSN-1.E.2: Redundancy is the inclusion of extra components that can be used to mitigate failure of a system if other components fail.
        • -
      • CSN-1.E.3: One way to accomplish network redundancy is by having more than one path between any two connected devices.
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      • CSN-1.E.4: If a particular device or connection on the Internet fails, subsequent data will be sent via a different route, if possible.
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      • CSN-1.E.5: When a system can support failures and still continue to function, it is called fault-tolerant. This is important because elements of complex systems fail at unexpected times, often in groups, and fault tolerance allows users to continue to use the network.
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      • CSN-1.E.6: Redundancy within a system often requires additional resources but can provide the benefit of fault tolerance.
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      • CSN-1.E.7: The redundancy of routing options between two points increases the reliability of the Internet and helps it scale to more devices and more people.
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      • - IOC-1.B.1: Computing innovations can be used in ways that their creators had not originally intended: -
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        • The World Wide Web was originally intended only for rapid and easy exchange of information within the scientific community.
          • -
        -
        • +
      • The Wikipedia article "Internet Protocol Suite" has a chart showing just a few of + the 300-odd protocols that run the Internet. You might let interested kids read up on + some obscure protocol and explain to the class what it does and why it's important.
        • +
      • The specific implementation of TCP/IP most commonly used around the world was developed + at UC Berkeley. :-)
        • +
      • It's easy to give a one-sentence description of a protocol, but, for example, early + implementations of TCP worked in theory but could easily become swamped with backed up + traffic; the current protocol description includes complicated timing mechanisms that + are essential to keeping the net flowing smoothly.
      -
    • + + + +
  • + Page 4: Who's In Charge of the Internet? + +
    • + + + + + +
    Are we cutting these assignments? If so, please delete HTML. --MF, 5/16/20
    + + +

    Solutions

    +
    + + +

    Correlation with 2020 AP CS Principles Framework 

    +
    +

    Computational Thinking Practices: Skills

    + +

    Learning Objectives:

    + +

    Essential Knowledge:

    + +
    + + -