Buttons: size and contrast — App development for students
Fingers are much bigger than a mouse pointer, so app buttons must be big enough to hit. In this course our rule is that every button is at least 48 px tall, with space between buttons so you do not tap the wrong one. Labels should be clear words like Save, and the colours need strong contrast — dark on light or light on dark. Yellow on white or light grey on white is hard to read, especially outdoors in bright sunlight.
Big and bold — “at least 48 px tall, spaced apart and in strong contrast”
Our rule: every button is at least 48 px tall. Missing px = 48 − height.
Leave space between buttons; use clear words like Save or Send.
Strong contrast (black on yellow, white on dark green) is easy to read; similar colours are hard.
Use it for: Designing buttons for any app, game or kiosk screen.
Worked example: 🔘 Our rule: buttons are at least 48 px tall. Which button is too small?
Next button: 48 px tall
Back button: 44 px tall
Done button: 64 px tall
Start button: 60 px tall → Back
48, 64 and 60 are all at least 48 — fine.
44 is less than 48, so the Back button is too small.
Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.
Right: 0 · Tried: 0
🏁 Lesson 12 test
20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.
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🔘 Tap Target Tuner badge when you pass — and a certificate when you finish all 8 lessons of
Part 2 · Designing Apps. You can still take the test without signing in.
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