Colour mixing and masking

Mix colours to see which colours mask others and how they combine to make new colours.
Science content
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Physics: Light and Sound (1)
  • white paint or ice cube tray
  • food colouring in dropper bottles (diluted: 5 drops dye in a small food dye dropper bottle, then fill with water)

Please note that in a class of students it is likely that one of them is at least partially colourblind (1 in 12 males are colourblind). As this is an activity distinguishing colours, these students will not be able to tell some colours apart and perceive some colours differently. The common red/green colour blindness means reds and greens (or colours containing reds and greens such as browns) look similar. More information at and

Add a drops of colours to the tray and look for new colours.

For a lesson on Fall leaf colours:
Use only yellow, red and green dyes.
Look for which colours can mask others - see attached worksheet.
The yellow is masked by both green and red.
A yellow pigment is always in green leaves, but is usually masked by the green pigment. In the fall, when the green pigment decays, the yellow is revealed, turning Fall leaves golden.
Red fall leaves also have yellow pigment. In these leaves the green pigment has decayed and new red pigment is made. The yellow is still hidden under the red, though sometimes leaves look orange when there is less red pigment and the yellow shows through a little.

Attached documents
Grades taught
Gr 1
Gr 2
Teaching site
Sexsmith Elementary