Working in a rural school with no electricity, no running water, and no transport was itself a learning experience, and necessity was proved to be the mother of invention, over and over again. Teaching science with almost no equipment was surprisingly good fun, forcing me to be creative and focus on the key principles.
This situation also provided my first exposure to materials development: I laboriously typed a colourful letter to complain about the standard textbook, and I was offered a contract to improve it. I believe my revision is still used and available in Zimbabwe, and also here.