Uśmiechający się starszy wykładowca wskazuje na coś o biały ekran z drewnianymi wskaźnik - Zdjęcie stockowe & obraz

Grey hair professor pointing on something at blackboard

Grey hair librarian holding book and leaning on shelf

Grey hair professor pointing on something at lecture hall

Expressive Senior Man with Bow Tie on White Background

Senior lecturer holding piece of chalk and looking away

Techniques for studying maths. protractor ruler. learn geometry easily. become good at math. stem in classroom. senior man teacher use tool at blackboard. bearded tutor in glasses. back to school.

Grey hair professor holding stack of books

Smiling grey hair professor holding stack of books with apple on top

Smiling senior man looking at camera while touching jacket isolated on grey

Smiling elderly man in eyeglasses and bow tie looking at camera isolated on grey

Cheerful retired man dancing with umbrella isolated on white

Grey haired man in shirt and jacket smiling at camera while holding laptop isolated on grey

Excited senior man in bow tie pointing with fingers at camera isolated on grey

Positive senior man talking on smartphone and pointing with finger isolated on grey

Confused senior man showing dubium gesture while looking at camera isolated on grey

Smiling elderly man with hand in pocket of pants talking on smartphone on grey background

Smiling senior man in shirt and jacket pulling hand at camera on blurred foreground isolated on grey