The shape of the lesson
By the end of the lesson, learners can
- The NIC and the MAC address: In the lab, look at a device's MAC address and IP address, and see what changes when it joins a different network.
- IP addresses: An IP (internet protocol) address identifies a device on a network so that data can be sent to it.
- The router: A home router sits between the devices in the house and the internet.
- NIC: needed to access a network; given a MAC address when manufactured.
- MAC: 48 bits, 12 hex digits, manufacturer code + serial code.
- IP: allocated by the network; static or dynamic; IPv4 32 bits, IPv6 128 bits.
- Router: sends data to a specific destination, assigns IP addresses, connects a LAN to the internet.
One picture every idea returns to
A computer needs a network interface card (NIC) to access a network. Each NIC is given a unique MAC address at the point of manufacture: 48 bits, usually written as 12 hexadecimal digits, made of the manufacturer code and the serial code. An IP address is allocated by the network to identify a device on it; it can be static (stays the same) or dynamic (can change each time the device connects), and is either IPv4 (32 bits) or IPv6 (128 bits). A router sends data to a specific destination on a network, can assign IP addresses, and can connect a local network to the internet.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Getting connected.. To join a network a computer needs the right hardware and two kinds of address. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 13 min | Teach and check: The NIC and the MAC address | In the lab, look at a device's MAC address and IP address, and see what changes when it joins a different network. Project tab 3 of the lab (NIC, MAC and IP addresses) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: IP addresses | An IP (internet protocol) address identifies a device on a network so that data can be sent to it. Model the worked example Valid or not? on the board, one line at a time. Your turn: Why was IPv6 introduced? | Pairs |
| 21 to 30 min | Teach and check: The router | A home router sits between the devices in the house and the internet. | Think-Pair-Share |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 17 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in The router, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Think-Pair-Share
Pose the question, give thirty seconds of silent thinking, then a minute to compare with a partner before a few pairs share with the class. The silent minute is the part that cannot be cut.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| The MAC address belongs to the NIC and is set when it is made. | It is not given by the network or the router: that is the IP address. |
| A router does more than "connect to the internet". | For full marks, give its specific roles: forwarding data to a destination using IP addresses and assigning IP addresses. |
NICs, MAC addresses, IP addresses and routers: worksheet
6 questions, 17 marks. Written in the style of the papers; no past paper question is reproduced.
Describe the structure of a MAC address.
Explain the purpose of an IP address.
Describe two differences between IPv4 and IPv6 addresses.
A company's web server must always be found at the same address. State whether it should have a static or dynamic IP address and explain why.
Describe three roles of a router in a home network.
A laptop is taken from home to school. State whether its MAC address and its IP address will change, and explain why.
Answer key and marking notes
- It is 48 bits long, usually written as 12 hexadecimal digits (6 pairs).
- The first part is the manufacturer code.
- The second part is the serial code of the device.
- It identifies a device on a network.
- So that data can be sent to (and from) the correct device.
- IPv4 is 32 bits; IPv6 is 128 bits.
- IPv4 is written as 4 denary numbers (0 to 255) separated by full stops; IPv6 as 8 groups of 4 hex digits separated by colons.
- IPv6 provides far more addresses than IPv4 (2128 compared with 232).
- (Any two differences, each with both sides.)
- Static.
- A static IP address does not change, so users (and DNS) can always find the server at the same address.
- It sends data to a specific destination on the network (using IP addresses).
- It assigns IP addresses to devices that connect.
- It connects the local network to the internet.
- The MAC address will not change, because it is fixed to the NIC at manufacture.
- The IP address will (probably) change.
- Because the IP address is allocated by the network it joins (a dynamic address from the school's network).
6 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
When is a device's MAC address given to its network interface card (NIC)?
- Aat the point of manufacture
- Beach time the device joins a network
- Cwhen the router assigns it
- Dwhen the operating system is installed
A MAC address is 48 bits long. How many hexadecimal digits are needed to write it?
- A12
- B6
- C48
- D24
Which of these is a valid IPv4 address?
- A172.16.254.1
- B192.168.300.4
- C10.0.0.256
- D192.168.1
Which is a role of a router?
- Ato forward data to its destination using IP addresses and to assign IP addresses to devices
- Bto give each NIC its unique MAC address when the device is made
- Cto convert analogue signals from sensors into digital data
- Dto store the start-up instructions that load the operating system
An IPv6 address is written as 8 groups of 4 hexadecimal digits, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334. How many bits does it contain?
- A128
- B32
- C64
- D256
A company runs a web server that customers must always be able to find, and staff laptops that connect to the office network each morning. Which type of IP address suits each?
- Aweb server: static; staff laptops: dynamic
- Bweb server: dynamic; staff laptops: static
- Cboth static, because every device needs a unique MAC address
- Dboth dynamic, because routers can only assign dynamic addresses
Quiz key
A MAC address is set in the NIC when it is made and stays the same for its life. Being given an address each time the device joins a network, or by the router, describes a (dynamic) IP address. Installing an operating system does not create a MAC address.
One hex digit represents 4 bits, so 48 ÷ 4 = 12 hex digits (written as 6 pairs, for example 00-1A-2B-3C-4D-5E). 6 is the number of pairs, or 48 ÷ 8 (bytes), not digits. 48 counts bits, and 24 divides by 2 instead of 4.
An IPv4 address has 4 denary numbers separated by full stops, each from 0 to 255 (8 bits), and 172.16.254.1 meets both rules. 300 and 256 are bigger than 255, so 192.168.300.4 and 10.0.0.256 are invalid, and 192.168.1 has only three numbers.
A router reads each packet's destination IP address and forwards it, can assign (dynamic) IP addresses to devices that join the network, and connects a local network to the internet. MAC addresses are set by the manufacturer, not the router. Converting analogue signals is an ADC's job and start-up instructions are stored in ROM.
8 groups × 4 hex digits = 32 hex digits, and each hex digit is 4 bits, so 32 × 4 = 128 bits. 32 is the number of hex digits (and also the size of an IPv4 address), 64 treats each hex digit as 2 bits, and 256 treats each as 8 bits.
A web server needs a static IP address so it can always be found at the same address. Laptops that join and leave can have dynamic addresses, allocated each time they connect and reused when they leave. The reversed pairing gets both wrong. MAC addresses are separate from IP addresses, so they do not decide static or dynamic, and a server can be given a static address even though routers often assign dynamic ones.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.