This hands-on activity, outlined by CS-unplugged, integrates components of visual arts and digital technologies to help students explore and apply the concept of digital image representation through use of the binary number system. During this activity, students practise using the binary number system to encode (create) and decode (identify) images by representing black pixels as 0 and white pixels as 1. This activity has been designed for Year 3/4 students; however, it can be easily altered to cater for other year groups by increasing/decreasing the complexity of the images and/or number of colours being used.

https://csunplugged.org/en/topics/image-representation/unit-plan/colour-by-numbers/