# How to effectively use colors on a whiteboard?

I will be teaching assistant for an analysis course next semester: I'll present the solutions of the exercices to the class. Syllabus is sequences and series of functions, Riemann and Lebesgue integrals, L^2 spaces, etc. Solutions of the harder exercices can get lenghty and technical.

I'd like to use colors to liven up the board, highlight the structure of the demonstrations and make technical manipulations easier to follow.

Do you have examples/tips of what to do and not to do?

• Use a lot of black, blue, purple. These are easy to see if the markers are fresh. Also, don't be afraid to use your own cloth and spray liquid to clean the board as you go. Nothing more annoying than to work over smudges. Red and green are pretty, but, beware some of these are at times hard to see, I also have trouble with orange and lite green... brown is ok. Aug 8 '17 at 18:56
• Since students are unlikely to be taking notes with multiple colors it is likely that what they will have to study from would be the black and white version of whatever you write. Thus no content should depend on the choice of colors. One thing you can do is to use color as a sort of mark-up, writing down important equations and inequalities that you will refer to later in a different color from the bulk of the writing. Aug 8 '17 at 19:59
• Quite minor [but]: For dotted lines, I usually draw them in as hard lines and then use my finger to erase bits of them. There are probably several cases in which some sort of erasure technique makes illustrating particular figures easier. [E.g., I do something similar for combinatorial problems involving arrangements of matchsticks and their counting.] Aug 9 '17 at 21:02

When teaching complex numbers I used one colour for imaginary parts of the numbers and another for the real parts.

More generally, whenever you have a clearly distinguishable object, you might to assign it a colour. If a sequence of functions is approaching a limit, you might make the limit blue. The sequence might be red.

A few points to keep in mind:

• Be absolutely consistent. Come up with a silly justification for the colours, or use some other mnemonic, and refer to previous notes.
• Green-red colourblindness is not that uncommon, I think. Check this.
• The colours should be a useful aid, and nothing should rely on them for understanding. This is for the previous two reasons, and also because you might not always have the colours available.
• Your second and third points are extremely important. I wrecked a lecture for some poor kid when I was first starting out by using red and green. After the lecture, he told me that he was red-green colorblind, and that the lecture had made no sense to him. I felt like such an ass. :\ Aug 8 '17 at 14:11

Last semester I purchased lots of different colors, and used them liberally. I could not be as disciplined and as careful as Tommi Brander's impressive control. But certainly distinct parts of geometric drawings, labels of vertices and labels of edges, any objects of distinct categories, were easy choices for different colors.

Some of my students took notes using colored pencils. Some took phone-photos of the more complicated constructions.

Incidentally, 8% of males and fewer than 1% of females are color blind.