FORM I, Junior Grade, learned to classify colours as belonging to one or other of six familiesthe red, orange, yellow, green, blue, or violet family. When these pupils reach Form I, Senior Grade, they have become fairly familiar with these colours through making them with crayons or chalk or naming them when found in specimens and materials of various kinds. They should be given an opportunity now, to discover and enjoy these colours in the glory of that perfect purity in which they appear in the spectrum.
For this lesson, a sunshiny day, preferably one shortly after a rainbow has been seen, should be chosen. On the day of the lesson or some time previously, each pupil should arrange the six colours in their proper order in a row of squares or oblongs on a sheet of drawing paper, making each spot of colour as brilliant as the crayon or chalk will make it. When the row of colours is complete, if they have had the good fortune to see a rainbow recently, they should be led to talk about the colours that were displayed in it. The teacher should contrive to set them wondering where the colours in the rainbow came from and where they went when they disappeared.
When the pupils have been told that these beautiful colours are in the light all the time, and that they are revealed only under certain conditions, the teacher might ask the question : ” How many would like to see the lovely spirit colours in the light, now ?” Of course the desire to see them would be unanimous. They might then be shown the prism and allowed to examine it, while the teacher divulges the secret that this little three-sided piece of glass can be made to separate the colours in the light so that they can be seen in all their beauty. Then the prism should be suspended in a window in the sunlight, so that the glowing colours will appear on the opposite wall. If the wall is not white, a sheet of paper should be fastened on it for the time being, in such a position that the colours will appear on it. The pupils should then be allowed to point out the different colours, naming them and showing their relative position in the spectrum. They should also compare them with the brightest colours they have been able to make with their crayons.