DSE ICT — Wireless Networking and Mobile Communications Teaching Guide (for tutors)

DSE ICT — Wireless Networking and Mobile Communications Teaching Guide (for tutors) | Band choice, speed conversion, WPA3

2026-11-02

Tutor lesson-prep guides · Secondary ICT

Students say 5G is fast but cannot explain why 5 GHz Wi-Fi is not 5G, or why 867 Mbps does not download 100 MB in a tenth of a second. This lesson fixes three conversions.

Objectives — Students can: (1) compute wavelength with lambda equals c over f for 2.4 and 5.0 GHz, giving 12.5 cm and 6.0 cm, and explain weaker penetration; (2) convert theoretical to practical speed, 867 Mbps times 0.5 gives 433 Mbps, so 100 MB takes 1.8 seconds; (3) state how WPA3 differs from WPA2 and why hiding the SSID is not security.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Bits and bytes	How many bits in a byte	Eight, so divide speed by eight
Frequency units	One GHz in hertz	Ten to the power nine
Network terms	What is an SSID	The network name, up to 32 characters

02 Lesson flow (45 minutes)

Time	Stage	Tutor does	Student does
0-6 min	Diagnostic three	Ask 2.4 versus 5 GHz, and 5G versus 5 GHz	Answer orally, write it down
6-16 min	Wavelength and penetration	Model lambda equals c over f twice	Compute both wavelengths
16-24 min	Channel planning	Draw the 83.5 MHz band, mark 1, 6, 11	Explain why channel 2 collides
24-34 min	Speed conversion	From 867 Mbps to 1.8 seconds	Three file sizes
34-42 min	Security comparison	WPA2 four-way handshake against WPA3 SAE	Fill the comparison table
42-45 min	Exit check	Three items marked live	All three right before leaving

03 Teaching script (read it out)

Scene 1: Higher frequency is not better reception

Lambda equals c over f: 2.4 GHz gives 12.5 cm, while 5.0 GHz gives only 6.0 cm.
A shorter wavelength diffracts and penetrates less, so 5 GHz is faster in one room but drops faster through two walls.
Answers must say under the same conditions, because coverage and speed trade off.

Ask students: which band through two walls, and why.

Scene 2: Channels are not free choice

The 2.4 GHz band offers about 83.5 MHz; one channel uses 20 MHz; there are 13 channels but only 3 non-overlapping ones, namely 1, 6 and 11.
Choosing 2, 4 or 7 guarantees overlap with neighbours, which is exactly what a Wi-Fi analyser shows as co-channel interference.
The common trap is thinking any channel change removes interference.
2.4 GHz also shares the band with microwave ovens near 2.45 GHz and with Bluetooth.

Ask students: name the three non-overlapping channels and say why.

Scene 3: Security is about the handshake, not the password alone

WPA2 uses a four-way handshake with AES; WPA3 uses SAE, so offline dictionary attacks largely fail and open networks are encrypted too.
Hiding the SSID only stops the name being broadcast, and MAC filtering can be spoofed.
A WPS PIN has roughly 11000 combinations, so at one attempt a second it falls in about 3.1 hours, which is why WPS should be off.
Peak mobile rates: 2G 0.1, 3G 2, 4G 100, 5G 1000 Mbps, so 5G is about 10 times 4G.

Ask students: which step does WPA3 improve.

04 Question types and worked steps

Type	Example	Steps	Answer
Calculation	Wavelength at 2.4 GHz	Lambda equals 3e8 over f, convert to cm	12.5 cm
Calculation	Download 100 MB at 433 Mbps	MB times eight divided by Mbps	1.8 seconds
Comparison	2.4 GHz against 5 GHz	Speed, range, interference	One conclusion per row
Security	WPA2 against WPA3	Handshake, offline attack, open networks	Three contrasts

Sanity check (teach this): Separate Mbps from MB per second and divide by eight.
Discount theoretical figures: 867 Mbps is practical about 433 Mbps, so label theoretical and practical.
5 GHz Wi-Fi and 5G mobile are different things.
Millimetre wave at 28.0 GHz has a wavelength of only 10.7 mm and reaches about 300 m, against about 1000 m at sub-6 GHz, a factor of 3.3.

05 Independent practice (3 questions)

Question	Answer	What to watch
Wavelength at 2.4 GHz	12.5 cm	3e8 divided by 2.4e9 is 0.125 m
Time for 100 MB at 433 Mbps	1.8 seconds	100 times eight divided by 433
5G peak over 4G peak	10 times	1000 divided by 100

06 Common mistakes and what to say

Mistake	Student writes	Say this
Mixing bits and bytes	433 Mbps means 433 MB a second	Divide by eight, so about 54 MB a second.
Assuming 5 GHz is always better	Everything should move to 5 GHz	It is faster but 6.0 cm penetrates poorly, so use 2.4 GHz at range.
Picking a middle channel	I moved to channel 3 so there is no interference	Only 1, 6 and 11 do not overlap in 2.4 GHz.
Hiding the SSID as security	Turning off broadcast keeps people out	It only hides the name; use WPA3, a long passphrase and WPS off.

07 Homework (paper, section and question numbers)

Practice: wireless configuration and channel planning — Name the three channels and justify
Practice: speed conversion with mixed MB and Mb units — Divide by eight first
All lesson-prep guides — Compare the ten-section structure

08 Exit check (last 5 minutes)

Question	Answer	Decision
Wavelength at 2.4 GHz	12.5 cm	All three right: move on
100 MB at 433 Mbps	1.8 seconds	One wrong: redo conversion
5G peak over 4G peak	10 times	Two wrong: back to act three

09 Tutor FAQ

Is wireless networking too early at S5

Wavelength and speed only need multiplication and division, so it is one of the safest scoring sections.

Which generation matters

Know both: 100 and 1000 Mbps are peaks, not real throughput.

Is there practice material

The homework links the in-site ICT practice pages with matching item numbers.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.