From Chapter 2: Your First Class (read the entire chapter)

Writing on the board is less common than it used to be. Most classrooms have a digital projector making it very easy to show slides that you’ve pre-filled with information. Having everything on the slides can be helpful, especially for a new teacher. You can think everything through ahead of time: what information to include, what order to present it, etc. Having everything in the slideshow means you can rely less on your notes and memory. The decision of whether to use slides may not be up to you. If you are part of a large multi-section course, there may be a standard set of slides that every TA is expected to use.

"If you try to write on a chalkboard or whiteboard the way you write on paper, it will be slow, difficult to read, and your hand will get tired."

Even if you do you use slides, the chalkboard or whiteboard is still a useful tool in teaching and it’s worth thinking about how best to incorporate it. There may be times when writing on the board is necessary or preferred. For example, having a written outline of the session on the board can help you and students stay organized. Equations or vocabulary that you want the student to access throughout the session can be written on the board as a reference. Even if you have a slide presentation, students may ask for clarification or more detail that require writing or drawing.

We write on paper using fine movements of your hand and wrist. If you try to write on a chalkboard or whiteboard the way you write on paper, it will be slow, difficult to read, and your hand will get tired. Writing on the board is more like drawing than writing. Take a tip from artists–when you write on the board, keep your hand and wrist mostly still and move from your shoulder. This takes a little practice, and your board writing won’t look much like your handwriting; however, you’ll find this lets you write faster and more legibly.