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Colour by Numbers: Image Representation

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    Computer Science Unplugged

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Colour by Numbers: Image Representation

This activity shows learners how computers use numbers to represent pictures. A grid is used to represent the pixels (short for picture elements) of a computer screen. Numbers indicate whether pixels should be black or white. Learners decode a few pictures and create their own and as an extension can create a color picture beyond just black and white. The activity references fax machines, but the same principles are used by all computer-driven displays.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
1 cent - $1 per student

Age Range:
Ages 6 - adult

Resource Types:
Activity, Lesson/Lesson Plan

English, French, Italian

Materials List (per student)

  • OHP (Overhead Projector) transparency made from OHP Master: Colour by numbers (page 16)
  • Worksheet Activity: Kid Fax (page 17)
  • Worksheet Activity: Make your own picture (page 18)


  • Engineering and Technology
    • Computing
      • Computer Science
    • Engineering
      • Computer Engineering
  • Mathematics
    • Data Analysis and Probability
      • Data Representation

Informal Categories

  • Arts and Crafts
  • Computers


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


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