This exercise relates to colour relationships - how colours work together and in what proportions they work best. Colours opposite each other on the colour circle are deemed to be complementary, as in they work well together and are easy on the eye; in a similar way to how an major chord on a guitar is easy on the ear. There are 3 complementary colour relationships:
Yellow and Violet
Red and Green
Blue and Orange
J.W. von Goethe, a German poet and playwright, suggested that depending on a colour's 'brightness' it should be allocated a number, the higher the number, the brighter the colour. These numbers were Yellow 9, Orange 8, Red 6, Green 6, Blue 4, Violet 3. So red and green worked best together in equal proportion, and violet and yellow should be approximately 3 parts violet to 1 part yellow. Of course these figures are not set in stone and were a result of von Goethe's own subjective feelings but it is a good starting point for mixing colours in photography.
Below I have made 3 images for the complementary pairings mentioned above and I have tried to keep them in the proportions suggested by von Goethe.
The next part of the assignment was to make 3 or 4 images where the colour relationships worked well subjectively but were not the complementary relationships we have been taught are correct.