There are few jobs where the passage of time is as noticeable as teaching, especially if you stay in the same town or school for your entire career. When I began my career in 1987, I could not possibly have imagined the changes I would witness as my career progressed.
Most of the changes came slowly and were mostly unnoticeable. Maybe they were unnoticeable because my attention was focused on building a career. Maybe they were unnoticeable because I was focused on raising my son. Or maybe I was just less observant when I was younger. Be that as it may, the changes did come.