Siwe włosy profesor prowadzące księgę i wskazując na coś na tablicy - Zdjęcie stockowe & obraz

Thoughtful senior lecturer sitting at table with pencil and notebook

Rear view of senior lecturer writing something on blackboard with piece of chalk

Grey hair professor holding stack of books with apple on top

Cropped image of senior professor pointing on something with pencil on blackboard

Portrait of smiling grey hair man looking at camera at home

Pensive schoolgirl holding pencil while thinking near notebook in classroom

Pensive handsome grey hair man thinking and looking at chessboard at home

Cropped image of professor drawing with piece of chalk at blackboard

Offended schoolgirl standing with crossed arms near chalkboard with equations

Schoolboy pointing at copy space next to chalkboard

Pensive senior man with grey hair standing with crossed arms at home