The unused classroom is a therapy room.

Most people assume the egg man to be kris’s therapist. But why is it that every time the man shows up, a tree from chapter one shows up too?

I believe that whatever kris went to therapy for, it was at school. And where was it? In the unused classroom. That’s why there are so many toys in there, and why kris has plenty memories of playing with them.

I don’t have evidence for this theory other than my own personal life. When I was young and I had a not so good day, i’d go to the social worker during school and Id play with toys and stuff as they talked to me. I believe kris went through this as well. That’s why they always see the egg man with the tree, because they were getting therapy in the unused classroom.