Keywords
55-60, 55-60 years, adult, away, blackboard, blue, caucasian, caucasian ethnicity, classroom, education, equipment, ethnicity, explaining, front, front view, gray, gray hair, hair, high, high school student, hold, holding, indoors, instruction, instructor, look, looking, looking away, mathematics, mature, mature adult, mature men, men, open, pen, people, person, presentation, projection, projection equipment, projection screen, purestock, school, screen, script, shadow, shirt, shirt and tie, stand, standing, student, teach, teacher, teaching, textbook, tie, tilt, two, two people, unrecognizable, unrecognizable person, view, waist-up, western, western script, years, stock image, images, royalty free photo, stock photos, stock photograph, stock photographs, picture, pictures, graphic, graphics, fine art prints, print, poster, posters, mural, wall murals, 1574r-015099, 1574r 015099, 1574r015099