Immagine ritagliata del professore che disegna con un pezzo di gesso alla lavagna - Foto e immagini stock

A teacher writes the Pythagorean theorem equation on a black chalkboard while teaching a group of students in a classroom

Grey hair professor drawing with piece of chalk at blackboard

Young teacher asks students

Portrait of caucasian senior teacher

Close up of business person hand measuring

Mathematical formulas on dark black chalk board closeup

Cropped view of man writing numbers with chalk on blackboard

Cropped view of man with chalk writing numbers on blackboard

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

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

Panoramic shot of man writing with chalk on blackboard

Arithmetic numbers on green school chalkboard

Cropped view of african american teacher writing on chalkboard