Technologies K–10 · Years 1–2
Pictures from numbers: shading a pixel grid from a code
Digital Technologies (NSW Science and Technology K–6, 2017); Digital Technologies: Knowledge and understanding, Data representation (ACARA v9)
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The idea
A picture can be stored as rows of 0s and 1s, where each digit says whether one square (a pixel) is left white or shaded.
What you need
- 8 × 8 grid sheets with 1 cm squares, 2 per learner
- Code card with 8 rows: 00111100, 01000010, 10100101, 10000001, 10100101, 10011001, 01000010, 00111100
- Grey lead pencil and eraser
- Blank code cards for learners' own pictures
How to do it
- Read the first row of the code from left to right. Shade the square under each 1 and leave each 0 white.
- Work down the rows one at a time, ticking each row on the card when it is done.
- Count the shaded squares in each row and write the number beside the row.
- Compare your picture with a partner's square by square.
- Change one digit in the code, shade a new grid and find the one square that changed.
- Design your own 8 × 8 picture, write its code and give it to a partner to shade.
What you should see
The shaded squares make a smiley face with 26 shaded and 38 white squares out of 64; the rows hold 4, 2, 4, 2, 4, 4, 2, 4 shaded squares from top to bottom. The learner knows it worked when their grid matches a partner's square for square and changing one digit changes exactly one square.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- A computer stores a picture as a tiny photograph (it stores a number for every pixel).
- More detail needs bigger squares (it needs more, smaller squares).
- The code and the picture are different information (the picture can be rebuilt exactly from the code).
Safety card
Hazards
- None beyond normal classroom activity
Controls
- Not applicable
Note
No chemicals or heat.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Science and Technology K–6 Syllabus (2017), NESA. The syllabus taught in 2026; the 2024 syllabus replaces it from 2027. Code read from the official syllabus document (DOCX) on 2026-09-22.ST1-11DI-T
- Science and Technology K–6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST1-DDT-01
- Australian Curriculum v9AC9TDI2K02
Sources
The pages the author read to write this activity.