Military training stuff has to be accessible. Here's Frank Wilczek:
WHEN I WAS ABOUT TO BEGIN TEACHING at Princeton, my friend and mentor Sam Treiman called me into his office. He had some wisdom to share. Sam pulled a well-worn paperback manual from his desk and told me, "During World War Il the Navy had to train recruits to set up and operate radio communications in a hurry. Many of those recruits were right off the farm, so bringing them up to speed was a big challenge. With the help of this great book, the Navy succeeded. It's a masterpiece of pedagogy. Especially the first chapter. Take a look."
He handed me the book, opened to the first chapter. That chapter was titled "Ohm's Three Laws." I was familiar with one Ohm's law, the famous relation V = IR that connects voltage (V), current (I), and resistance (R) in an electric circuit. That turned out to be Ohm's first law.
I was very curious to find out what Ohm's other two laws were. Turning the fragile, yellowed pages, I soon discovered that Ohm's second law is I = V/R. I conjectured that Ohm's third law might be R = V/I, which turned out to be correct.