Arranging coloured tiles according to chroma

DESCRIBING COLOURS:
Lightness/value and Chroma

Sort hue families by the chroma attribute

Details:

• Middle-high school and up

• Time: 25 minutes

• Learning Outcomes: Identify chroma of various coloured tiles, and arrange tiles from decreasing to increasing chroma.

• Colour Concept: Realize that chroma is one of colour’s attributes, and distinguish it from lightness/value.

Materials:

• Coloured tiles: physical, or online at: https://5drealities.itch.io/colour-lit-sorting (CHROMO)

Instructions:

See Free Sort Lesson plan for instructions on using online CHROMO sorting set.

This exercise can immediately follow the Arranging coloured tiles according to lightness/value exercise. Please see that exercise to begin, and arrange a hue family next to a greyscale, with each coloured tile matched to its ‘grey partner’ or lightness/value. See Figure 1.

• Now that you have identified the lightness/value, you will arrange the tiles according to their chroma. The chroma of a colour is best defined as its degree of departure from a grey of the same lightness/value.

• Arrange the tiles in the central area with the most chromatic tiles on the right and the least chromatic tiles (closest to grey) on the left in the following manner:

• As the vivid green has the highest chroma in the green hue family, move this tile farthest to the right, keeping it level horizontally with its grey partner. Then move the other tiles to the right of the grey scale, to positions that you judge to be their relative degree of chroma. See Figure 2.

• Note: You will have to establish your own scale initially, but when you have other colours for comparison it will be easier. For example, you will be able to judge whether the vivid colour from one hue family is more or less vivid (has higher chroma) than the vivid colour from another hue family.

• Now take a photograph or a screen shot and post or send it to the teacher/ workshop leader for display and discussion.

• Repeat this process with other hue families. Record each hue family group as you go and post or send it to the leader of the workshop for display and discussion. See Figures 3-4 for more examples.

Vocabulary:

Lightness/value, Chroma

Questions & observations:

• Which hue family was easiest to arrange in chromatic order? Which hue family was hardest?

• Which vivid tile has the highest chroma? Which has the lowest chroma?

• Which tile overall has the highest chroma? Which has the lowest chroma?

What’s going on?

• The colour attribute known as chroma is one of the three dimensions of colour, along with hue family and lightness/value. The purpose of this exercise is to understand the importance of the chroma of a coloured tile in order to fully specify its three-dimensional description.

• Chroma is an indication of the chromatic component (or degree of vividness) of a colour, while lightness/value is an indication of the how light (pale) or dark a colour is, relative to a perfect achromatic grey.

• Visually estimating chroma is a more difficult task to do than visually estimating lightness/value. Answers for visual chroma assessments can differ among observers. This is to be expected. The visual assessments of chroma should be similar but variability among observers is common. The only way to get accurate chroma values is to measure the samples and this goes beyond the scope of what this exercise is intended to accomplish.

Find out more:

• For a deep-dive into chroma, see David Briggs’ website entry on The Dimensions of Colour: Chroma