This past week, during Brown's Spring break, I gave a couple of lectures at a Spring school in France on theoretical computer science.
It took place on an island off the Atlantic coast, in a campground about a mile from lovely beaches of fine sand. There were slightly more than 40 students, postdocs, and researchers there to learn from the lectures, and a half-dozen lecturers, a ratio of about 7 to 1. The weather was amazing, with bright sun and exceptionally high temperatures every day, and so, instead of observing the usual lecture format, the school improvised ad hoc Socrates-like discussions: every morning we split into small groups, with one instructor per group, got on our bikes and headed to the beach. On the beach, we formed small circles and had learned conversations about algorithms, graphs, and randomness. But how can one teach without a screen, one might ask? The answer has been known since Antiquity at least: wet sand and a stick are the perfect writing medium. I only got into trouble once on the first day, when, half way through the analysis of the Goemans-Williamson maxcut algorithm, a wave came in and erased my calculation, as well as accidentally getting me wet all the way to my knees. Instead of erasing the board when we needed more writing space, we simply walked along the shore to find the next fresh spot of unwritten wet sand. At lunch time, the staff from the compound brought us picnic lunches and some wine (two bottles for every 6 people, usually one of local wine from the island, and the other one from the Bordeaux region). After going through the presentation of an exciting result, we cooled off by running in and out of the water (everyone had brought a swimming suit, of course). In the early afternoon, we took a leisurely walk back to our bungalows, walking our bikes and discussing exercises and puzzles as we went, then took a pleasant nap (or tried to use the flaky internet connection) before heading back to the beach for the late afternoon work session and evening swim. On the last day, we switched roles: the students became the instructors, the instructors became the students, and we got acquainted with the tricks of riding bicycles in the sand, juggling torches of fire (if you get petrol on your clothes, dive into the sand and other will quickly cover you with sand to extinguish the flames), getting into cold water without effort, body-surfing the waves, and biking in the woods by night without a light. At one point Ronald de Wolf commented: "We look like a bunch of hippies!", but I could not tell whether his tone was one of approval or of disapproval.
I taught a bit of optimization, and we practiced steepest descent by rolling down the sand dunes. Someone else presented an analysis of the dynamics of the famous sandpile model, and we had a lab session testing the fit of the model with reality (it's a poor fit). But the main theme of the week was randomness and probability in algorithms, and we used waves as our random coin flips, checking how long it took to get wet as a practical instance of geometric distributions. We studied random walks by biking into the confusing salt marshes area, where an unhappy landowner once threatened to keep me as a hostage for intruding on private property. We learned the similarity between having a creative idea and seeing a shooting star: both require much patience, skill in knowing where to look, and a little bit of luck. In both cases, two persons can both be star gazing at the exact same time with the same dedication, and one will see the shooting star but the other one won't. We tested our students' ability to greet new ideas with an open mind, by giving them oysters for dinner. We suffered the predictable consequences of our hard work all week: sun burns, sore muscles, and a big pile of unread emails. But all in all, I would not complain.