Teachers are most likely to notice that overt hyperactivity decreases while students still struggle with attention and emotion control. In adolescence, ADHD often looks less “busy” and more internally restless.
Most likely observed change
The key change a teacher is most likely to observe is hyperactivity transitioning to more subtle restlessness, with continued inattention and ongoing difficulties regulating emotions. Adolescents may fidget, seem internally agitated, miss details, lose focus, and have stronger emotional reactions, even though they may no longer run around or leave their seats as often as in childhood.