Couple things.
A rainbow is actually not discrete, but has the full range of wavelengths spread out. If you have a non-colourized camera, you will see this in the shots.
What the eye sees in a rainbow are distinct bands that represent different sensitivities in the eyes. ROYGBIV. There’s reasons for each one that can be explained as to why it was important for the eye to distinguish between each one.
Now,try teaching optics to someone who’s never been taught that the difference between red and green is simply the wavelength of the light. First year student in college, and I swear I am telling the truth, had never been taught that colours correspond to different wavelengths.
As a freshman in college chemistry I was shocked my classmates could not do simple unit conversions. I almost cried of boredom because I teacher had to spend three weeks trying to teach these guys about molarity/molality/normality. They couldn't cross multiply, they had never heard of such a thing.
Cross multiplication. Really.
One of my favorite math teachers senior year of college confided in me that she frequently had students show up in her college algebra class who insisted that 1/7 was bigger than 1/5, or couldn't understand even other such pre-algebra concepts.
And that was just the math/science teachers. I minored in math but majored in English.
I did a peer review of one student's paper freshman year, and he wrote the phrase “acrost the street.” Also, students would actually WRITE “spost” [sic] instead of “supposed”. As an undergrad junior, I tutored a Master's student who could not understand where commas go. Her writing was really horrible, and so was her reading comprehension. I loved her; she was really sweet. I always wanted to ask her just how she managed to get her undergrad, though.
Learning about optics would be fun. Is that part of a physics class or computer science?