Hey! Teacher here! I’ve been through this so many times. I usually just say some variation of “I stutter sometimes. It’s just how I speak and something that’s different about me. Lots of people have differences that may seem weird at first.” I usually turn this into a question like “what’s something different about you?” Or “do you know anyone with any differences?” Depending on the age group you’re working with, you could go different ways with it.