The way I usually fix people who bizarrely think 0 is both even and goes like this: Me: OK, let's get started. Is 5 even or odd? Them: Odd. Me: And 4? Them:

The way I usually fix people who bizarrely think 0 is both even and goes like this: Me: OK, let's get started. Is 5 even or odd? Them: Odd. Me: And 4? Them: Even. Me: How about 3? Them: Odd Me: And 2? Them: OK, OK, I get it!