Common confusion between -pal and -ple
A principle has to do with ideas, not things. A principal of a school is such not because he or she is a person but because he or she is top dog. Anything that is the main or foremost thing is the principal one, unless it is an idea or something like that then it is a principle.
It's currently wrong -- it gives "principle colors" as the correct answer, and marks "principal colors" incorrect.
BUT it's "The principles of color theory" and "The principal colors of the painting are red, green, and yellow."
The principal of a school is short for the principal teacher -- principals mostly don't teach anymore, but they used to.
June 19, 2018.
Duolingo is consistently confused about principle and principal at present. As I posted above, it's "the principles of color theory" but "the principal colors of the painting are red, purple, black."
If you're using it as an adjective you want "principal" -- and note that "the principal" of a school is short for "the principal teacher of a school," so even in that usage, it was originally the adjective, and the noun has been dropped.
Mnemonic from Wiktionary: ""The principal alphabetic principle places A before E"."
June 19, 2018.
Sorry, DuoLingo, but the answer is either "princiPAL" or something else entirely. PrinciPAL means main, most prominent, leading, etc. "princiPLE" refers to foundational ideas, tenets, underlying causes, etc. This distinction was beaten into my head when I was eight years old. I would refer you to my third grade teacher, but I'm sure Ms. Peters has better things to do if she is still with us.
Duolingo has principle and principal confused currently.
When we study the principles of art, we learn to identify the principal colors of the painting. Or, from Wiktionary, "The principal alphabetic principle places A before E".
Please report if Duo is still INCORRECTLY saying this should be "principle colors"
Actually, not to be nitpicking but the primary colors in the light spectrum as captured by our eyes are rojo, verde y azul (azul specifically with the tint of violeta), while the ones used in printing are cyan, magenta y amarillo, never really red, green and blue (which is a surprisingly common misconception even among the art teachers). ;)
Anyone interested more in color theory can read a short explanation here: http://web.atmos.ucla.edu/~fovell/AS3/theory_of_color.html
Well, no; art teachers are a lot more correct than you think. Having worked in both worlds --
Printer and monitor inks map well to the RGB and CMY(K) color space maps -- they're carefully formulated and designed to do so, so that you can represent them nicely in hex and add and subtract them.
Traditional pigments suspended in painter's mediums don't need to be represented by computers, and aren't formulated to conform readily to, say ffff00 and result in a predictable color which can map exactly to 0000ff00, such that what you see on your monitor (if it's very good and very well adjusted) is what appears on your printer (also if very good and very well adjusted) and what your print shop will print (if you are OH SO LUCKY and have a great print shop.)
Artist's pigments are based on mineral pigments suspended in an artist's medium, and nobody needs to map them exactly to hexadecimal, or squirt them through a nozzle and have them come out well on 20lb Georgia-Pacific paper. Green pigments are difficult and problematic; good violets (magentas) often tend to fade and are expensive. You aren't going to get good results treating cyan and magenta as primary colors in this particular space.
Artist's pigments are also more or less transparent; the particles are of different sizes, and behave differently alone or when mixed with other pigments. They WILL combine very differently on your palette when you mix them than if you matched the two in CMYK space and combined them mathematically.
The end result is that, when you have a paint brush in hand, and an easel in front of you, a red-yellow-blue color wheel is really much more useful and helpful and accurate than trying to use RGB or CMYK.