Ключевые слова: add, arrow, axis, background, black, blackboard, board, border, business, chalk, chalkboard, chart, class, classroom, college, concept, data, design, diagram, drawn, education, element, elementary, flat, frame, graph, hand, highshool, horizontal, illustration, index, isolated, learn, lesson, mathematics, plank, room, school, seminar, teach, texture, university, vertical, white, x, y,