Once in a while I'd explain something in a slightly different way than the regular teacher did and a kid would suddenly have an AhHa moment and understand a concept they'd been struggling with. That was very rewarding to me.
It was also nice to be flexible with the freedom to take days off without hurting anyone else. And I didn't need to correct papers or make lesson plans, although I always had some general ones with me for the times a regular teacher hadn't left any or had been out so many days their plans all been used by previous subs.
But eventually I'd miss having my own class and watching the same kids progress from day to day so I'd go back to doing that. altogether I was a substitute teacher for a total of about four years.
I worked a lot with Special Ed classes since my experience qualified me for that. I'll share a couple of interesting stories about those classes in later posts.