Ключевые слова: a zerotolerance, blackboard, bullying, chalk, chalkboard, chemistry, class, concept, cubes, educate, education, elements, furnaces, green, harassment, images, instruct, learn, nobody, noone, objects, periodic, periodic elements, picture, pictures, policy, punishment, royalty free photo, rules, school, sexual, sexual harassment, stock image, stock photograph, stock photographs, stock photos, study, table, teach, tolerance, train, word, zero,