Nature - word written on a smudged blackboard

Keywords:

education, school, class, chalkboard, background, blackboard, black, chalk, board, lesson, texture, billboard, white, old, write, used, learning, concept, teaching, handwriting, grunge, knowledge, learn, English, Chinese, bilingual, characters, letters, smudged, dirty, erased, language, text, nature, word, natural, environment, ecology, sign, symbol, message, abc, idea, hand, letter, abstract, information, writing, translation,