Excerpt from an essay about lecturing at a summer school in Puerto Rico and visiting Arecibo.

I took a seat in the nose-bleed section of the auditorium, a few rows past the last students, and worked on my laptop and watched the lectures out of one eye.  I was scheduled as the second lecturer of the day, to begin after a mid-morning coffee break, and so I attempted to divine what worked with this audience and, more importantly, what did not.  The school was completely set up for lecturers to display slides on a projection screen and talk through the formulas and plots in an attempt to teach the eager students.  There simply don’t exist very simple, compact mathematical expressions that are relevant for particle physics, and so lecturers had the tendency to casually show a slide with a formula in microscopic font extending from the left margin to the right, say a sentence about it, and move on to the next slide representing the next step in a logical progression, expecting that students caught all of that.  I have never been satisfied with this style of lecturing, as all of these students can read all about the most complicated mathematical formulas in some dense, weighty tome.  What a book cannot provide is the energy, enthusiasm, and excitement of the everyday micro-discoveries that abound in physics and ultimately make doing it so fun.  I had requested to the organizers that I would like to present my lectures on a blackboard, writing important terms and equations at the same pace that students could digest them.  The organizers had obliged, expressing their gratitude that I had a grand plan for my lectures.  So, off to one corner of the stage, opposite the podium, they had provided a compact, rolling whiteboard.

The lack of slides untethered me from the podium, and I could walk around the stage discussing the physics I was entrusted to teach, quasi-scale invariant objects called jets that are manifestations of the strong nuclear force.  The story and motivation was easy to describe verbally augmented with hand gestures for emphasis, and I would occasionally write important points on the whiteboard for later reference.  Though increasingly becoming rare, large auditoria in physics departments would have a few to several columns of blackboards, with each column consisting of two or three boards that could be pushed around vertically.  This set up ensured that the past hour or so of notes would be visible to students at all times, and was easy for the lecturer to call back to earlier calculations by simply pointing at the appropriate board.  The whiteboard I was supplied was a mere six feet wide, though two-sided, so I could only write a few phrases or equations on each side, then flip it over for more on the back.  The precious space encouraged me to limit both what was written and what was erased, but the inevitable questions about the previous board degenerated my lecture into a near slapstick comedy of whirling the entire thing around and around and around.