Orange cube
PERCEIVING COLOURS:
Colour is contextual
Build an orange cube and notice how light affects colour
Details:
Middle-high school and up (Younger students will be able to do this exercise with solid-coloured blocks, without needing to build a cube.)
Time: 20 minutes
Learning Outcome: Recognize that the amount, type and direction of light falling on a surface impacts the colours we perceive.
Colour Concepts: The amount, type and direction of illumination of an object affects the colours we perceive.
Materials:
Scissors
Ruler
Glue or two-sided tape
Instructions:
Cut out each figure in the handout (A. Colour sample; B. Orange family; and C. 3D cube. Make sure to cut out the white tabs when you cut out the cube).
Fold your cut out of C. 3D cube along the dotted fold lines shown in the insert. You will get the best result if you use a ruler to make the folds sharp.
Build the 3D cube by attaching the tabs using glue or tape. (Make sure you don’t have tape on the outside of the cube.)
Observe how the appearance of each side of the cube changes depending on the amount of light it receives.
Note: the template can be easily reproduced in a variety of sizes. Large cubes may be more appropriate for younger students.
Figure 1. Template for orange cube.
Vocabulary:
Figure 2. Completed cube.
Questions & observations:
Compare the faces of the cube itself to A. Colour sample. Do they appear the same colour? If not, describe the difference? (Hint - use the character as a descriptor.)
How do the faces of the cube itself compare to the colours on B. Orange family? Do they appear the same colour? If not, describe the difference?
How does the amount of light received by a surface affect its appearance?
How does the direction of a light source affect a surface’s appearance?
How does the type of light source affect a surface’s appearance?
More to explore:
Look for a solid-coloured object (like a Lego block or a ball) around your house, and make the same observations.
Punch a small hole in a piece of cardboard (e.g. with a hole punch) and look at the various sides of the cube under different illumination. This will help better isolate the perceived colours.
What’s going on?
When we perceive any object, our visual system (made of our eyes, brain and all the connections in between) interprets the overall distribution or balance of light entering our eyes as an object with a certain colour, under illumination of a certain intensity and colour (including “white” or achromatic light). See Colour is a Perception.
Although the orange cube is built from a uniform-coloured piece of paper, when we look at it under varying amounts of illumination, the perceived colour of the light reflected from the cube changes. When less light falls on a surface, less light enters our eye to activate our visual system, and our perception of the colour changes. The area appears less bright and less colourful. Our visual system tends to interpret these perceived differences across the illuminated cube as belonging to the same coloured object, regardless of the illumination differences that we see. The colour we perceive as belonging to the cube itself is called its object colour.
Find out more:
See videos by David Briggs:
