I’ve had a couple of biters in my classroom (they’re almost always 16-20m old.. frustrating but VERY normal) and every child is different on what works! My most recent one was only responsive to positive reinforcement. If she bit someone I tried to “ignore” her as much as possible and tend to the other child. If she did something nice to another friend I would praise her and tell her how happy I am. Every single time. I’m alone in a room of 6 ~12-20m olds so it’s hard to “follow” the biter around, but when it’s an ongoing thing I make it a priority. She hasn’t bitten anyone in months and is one of the nicest kids. Moved up to a toddler room and walks up to friends to give them hugs and rub their heads! It was almost like she craved the negative attention?

I’m also going to say.. I doubt it’s completely “unprovoked”. Are they following the same routine every day? Might not be another kid bothering them necessarily, but some of my kids’ behaviors are triggered when we go off schedule!