Ключевые слова: advanced, aluminum, basic, black, chalk, chalkboard, class, classes, classroom, classrooms, college, course, educate, education, educational, electronics, elemntary, environmental, environmentally, friendly, glass, grade, green, heavy, instruction, introductory, lecture, metal, presentation, recycle, recycling, renewables, school, solar, teacher, teaching, technical, train, training, tutor, university, white, wind,