Worksheet

F12.6 The digital divide and accessibility

Technology and society · GCSE · OCR J277 1.6.1, AQA 8525 3.8, Edexcel 1CP2 5.1.1 · about 20 min

What this lesson is about

Who is shut out of technology, designing for disability, and measuring colour contrast.

• The digital divide
• Accessibility
• Measuring contrast

Questions 5 marks in all

1. [1 mark]What is the digital divide?

   1. AThe gap between those with good access to technology and those without
   2. BThe gap between fast and slow computers
   3. CThe difference between hardware and software
   4. DThe split between two networks

2. [1 mark]Why does the digital divide matter more now than 20 years ago?

   1. AEssential services such as banking and homework assume internet access
   2. BComputers are cheaper
   3. CScreens are bigger
   4. DThere are more games

3. [1 mark]Why is "errors are shown in red" a problem?

   1. ASomeone who is colour blind may not see the difference
   2. BRed is hard to print
   3. CRed text is slower to load
   4. DIt uses more power

4. [1 mark]Which helps a screen reader user most?

   1. AText alternatives for images
   2. BBrighter colours
   3. CMore animation
   4. DA larger mouse pointer

5. [1 mark]The accepted minimum contrast ratio for normal text is:

   1. A4.5
   2. B1.0
   3. C21
   4. D0.5

The task: check the contrast

Using the provided luminance, write contrast(a, b) returning the contrast ratio of two colours. For each (name, foreground, background) in pairs, print <name>: <ratio> pass if the ratio is 4.5 or more, or <name>: <ratio> FAIL if not, with the ratio rounded to 1 decimal place. At the end print failed: <n>, and set the LED to the foreground colour of the first pair that passes.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

def luminance(rgb):
    """How bright a colour looks, from 0 (black) to 1 (white)."""
    out = []
    for value in rgb:
        v = value / 255
        out.append(v / 12.92 if v <= 0.03928 else ((v + 0.055) / 1.055) ** 2.4)
    return 0.2126 * out[0] + 0.7152 * out[1] + 0.0722 * out[2]

# name, foreground, background
pairs = [
    ("grey on white", (150, 150, 150), (255, 255, 255)),
    ("navy on white", (0, 40, 120), (255, 255, 255)),
    ("yellow on white", (255, 220, 0), (255, 255, 255)),
    ("white on navy", (255, 255, 255), (0, 40, 120)),
]

Plan your program here, then type it in and press Run.

Do it on the robot
www.bugbotlab.com/learn/f12-6-the-digital-divide-and-accessibility/
The simulator checks it and tells you when it passes. Nothing to install, no account.

Challenges

1. Large text only needs 3.0. Which pairs pass at that level? Check grey on white with the ratio before rounding.
2. Why is "the error is shown in red" a problem, and what would you add?
3. Name three things a school could do about the digital divide for its own students.