You can go younger. I'm 33 and remember I was being teased in the hallway by my friends when we heard about the first plane and still thought it was an accident. I remember where I was when we found out it was an attack and the towers had fallen. I remember the teacher and the literal seat I sat in. I was in 11th grade and I am almost 34. I would imagine even middle schoolers and the time would remember 9/11.